November 30, 2020



 There is something fascinating and enticing to me about the idea of keeping an aquarium system "going" for very long periods of time, occasionally changing things up; leaving the "operating system" largely intact, while replacing the "soft" components over time.


Let's say that you're kind of over your Southeast Asian Cryptocoryne biotope, and ready to head West to South America.

So, rather than tearing up the entire tank, removing all of the plants, the hardscape, the leaves and botanicals, and the substrate, you opt to remove say, only the plants and the driftwood/rocks from the tank; exchange a good quantity of the water.

Woooah! Crazy! You fucking rebel...

I know. I know. This isn't exactly earth-shattering. 

On the other hand, in the world of the botanical-style aquarium, the idea of leaving the substrate and leaf litter/botanical "bed" intact as you "remodel" isn't exactly a crazy one. And conceptually, it's sort of replicates what occurs in Nature, doesn't it?

Yeah, think about this for just a second.

As we almost constantly discuss, habitats like flooded forests, meadows, vernal pools, igarape, and swollen streams tend to encompass terrestrial habitats, or go through phases where they are terrestrial habitats for a good part of the year.

In these wild habitats, the leaves, branches, soils, and other botanical materials remain in place, or are added to by dynamic, seasonal processes. For the most part, the soil, branches, and a fair amount of the more "durable" seed pods and such remain present during both phases. 

The formerly terrestrial physical environment is now transformed into an earthy, twisted, incredibly rich aquatic habitat, which fishes have evolved over eons to live in and utilize for food, protection, and complex, protected spawning areas. 

All of the botanical material-shrubs, grasses, fallen leaves, branches, seed pods, and such, is suddenly submerged; often, currents re-distribute the leaves and seed pods and branches into little pockets and "stands", affecting the (now underwater) "topography" of the landscape.

Leaves begin to accumulate. Detritus settles.

Soils dissolve their chemical constituents- tannins, and humic acids- into the water, enriching it. Fungi and micororganisms begin to feed on and break down the materials. Biofilms form, crustaceans multiply rapidly.  Fishes are able to find new food sources; new hiding areas to spawn.

Life flourishes.

Similar to what should happen in our aquaria, right?

The longer these materials are present in the ecosystem, the more they are utilized along the food chain by various aquatic life forms.

I have long believed that if you decide to let the botanicals remain in your aquarium to break down and decompose completely, you shouldn't change course by suddenly removing the material all at once...Particularly if you're going to a new version of an existing aquarium.


Well, I think my theory is steeped in the mindset that you've created a little ecosystem, and if you start removing a significant source of someone's food (or for that matter, their home!), there is bound to be a net loss of biota...and this could lead to a disruption of the very biological processes that we aim to foster. I think that we should continuously add more materials into the aquarium to replace those which have broken down.

Okay, it's a theory...But I think I might be on to something, maybe? So, like here is my theory in more detail:

Simply look at the botanical-style aquarium (like any aquarium, of course) as a little "microcosm", with processes and life forms dependent upon each other for food, shelter, and other aspects of their existence. And, I really believe that the environment of this type of aquarium, because it relies on botanical materials (leaves, seed pods, etc.), is more significantly influenced by the amount and composition of said material to "operate" successfully over time. As existing material break down, new ones are constantly being added back into the environment. 

Yeah, there is a natural "prototype" for this process.

And, in the aquarium, we can embrace this and replicate it.

This is similar to the Japanese aquascaping practice of "sozo haishoku" espoused by the "Master" of this in aquariums, the late Takashi Amano. This is the processs of removing of as much old substrate material as possible along with the plants it contains in an aquarium, and replacing them with new materials.

It preserves the overall "composition" of the layout, but the "softscape" (botanicals and leaves, in our case) could change dramatically.

As we talked about many times before, removing old materials and replacing them with new stuff does sort of mimic what happens in many streams and rivers on a seasonal basis: Older materials are swept downstream as the watercourses swell, and are replaced by new ones that arrive to replace them.

And of course, in the aquarium, performing a "sozo haishoku"-type replacement of materials can significantly change the aesthetic of the aquascape because the botanicals are replaced with different ones after the previous ones are removed. In Nature, the underwater "topography" is significantly affected by these events, removing old feats and replacing them with new ones.

On the "downside", it can also create significantly different environmental parameters when we do big "change-ups" of materials in a short span of time; the impacts on our fishes may be positive or negative, depending upon the conditions which existed prior to the move. 

Okay, I might just be torturing this simple idea to death- I admit this point that I'm probably not adding much more to the "recipe" here; likely simply being redundant and even a bit vague...However, I think we need to think about how interesting and indeed, transformative this simple practice is.

And yeah, I'll concede that we probably don't have every answer on the processes which govern this stuff.

For example:

The most common question I get when it comes to taking out a fair amount of this material and then "continuing" the tank is, "Will it cycle again?"

And the answer is...Sure, it could.

On the other hand, here is my personal experience:

Remember, I keep a sort of diary of most of my aquarium work. I have for over three decades (gulp...). Just random scanning my "diary", I see that I have executed this practice dozens of times in all types of aquariums, ranging from simple planted aquariums to hardscape-only tanks, to botanical-style, blackwater and brackish aquariums, to reef tanks.

Not once- as in never- have I personally experienced any increase in ammonia and nitrite, indicative of a new "cycle."


Now, this doesn't mean that I guarantee a perfect, "cycle-free" process for you.  I'd be a complete asshole if I asserted that!

On the other hand, by leaving the bulk of the substrate material intact, and continuing to provide "fuel" for the extant biotia by leaving in and adding to the botanicals present in the aquarium, this makes a lot of sense.

I personally think our botanical-style systems, with their diverse and dynamic biology, rebound quickly. Much like the natural systems they purport to represent.

Sure, I have in place a mindset and husbandry practices that assure success with this idea.

Personally, I don't think that botanical-style aquarium are ever "finished." They simply continue to evolve over extended periods of time, just like the wild habitats that we attempt to replicate in our tanks do...


Stay engaged. Stay creative. Stay bold. Stay excited...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


November 28, 2020


Exercises in functionality...Making a "mess?" Or building a microcosm?

One of the great things about playing with natural botanical materials in our aquariums is that, for many years, there has been no specific set of "rules" about how to do stuff. Nature enforces Her own rules- the processes by which nutrients are utilized, the growth of beneficial bacteria and fungi, the nitrogen cycle, food webs, etc. These are constructs that we cannot circumvent. 

Aquarium hobbyists have (by and large) collectively spent the better part of the century trying to create "workarounds" or "hacks", or to work on ways to circumvent what we perceive as "unattractive", "uninteresting", or "detrimental." And I have a theory that many of these things- these processes- that we try to "edit", "polish", or skip altogether, are often the most important and foundational aspects of botanical-style aquarium keeping!

It's why we literally pound it into your head over and over here that you not only shouldn't try to circumvent these processes and occurrences- you should embrace them and attempt to understand exactly what they mean for the fishes that we keep. They're a key part of the functionality.

Now, I've had a sort of approach to creating and managing botanical-style aquariums that has drawn from a lifetime of experience in my other aquarium hobby  "disciplines", such as reef keeping, breeding killifish and other more "conventional" hobby  areas of interest. And my approach has always been a bit of an extension of the stuff I've learned in those areas.

I've always been fanatical about NOT taking shortcuts in the hobby. In fact, I've probably avoided shortcuts- to the point of making things more difficult for myself at times! Over the years, I have thought a lot about how we as botanical-style aquarium enthusiasts gradually build up our systems, and how the entire approach is about creating a biome- a little closed ecosystem, which requires us to support the organisms which comprise it at every level.

Just like what Nature does.


My current little projects are just the latest iterations of my desire to recreate many of the processes which occur in Nature in our own aquariums, by letting her "do her thing.."

My wife and I are doing extensive renovations on our new home, which means that it'll be several months before we can fully move in, necessitating that most of our stuff is in storage until the work is complete. And that includes, of course, my home aquariums! 😱 I just have a few of my "nano-sized" tanks here- not the larger aquariums. So, what better use of my "down time" at home while waiting to set up the larger tanks than to try some new and unorthodox stuff with these little tanks?

So, what exactly am I working on?

Well, obviously, I have a few versions of my "Urban Igapo" tanks in play, experimenting with "wet" and dry season modes in an "igapo" display and a "varzea" display.

These are doing quite well, and are living up to their promise in every conceivable way! I've been fortunate enough to keep and spawn the interesting South American annual killifish, Notholebias minimus "Campo Grande" for two "seasons" now, and had the adults spawn in the tank for about 5 months before slowly drying it out (obviously, I removed the adults before doing this...😱)

This was my 12th "seasonal cycle" with this same aquarium- and the only real "edits" I've made were removing some bamboo seedlings that I didn't really like in there. I stayed with the marginal plant, Acorus, for the sole plant in this tank. These plants are now over three years old. They do beautifully transitioning between wet and dry phases...and when the killie eggs hatch out, it's always a real treat!

( I know, bad iPhone shot..but hey- this is the 2nd generation of annual killies I've hatched out and reared in this one "varzea" aquairum!)

I believe that the "Urban Igapo" approach that (I dear say) we created and have been playing with for about two years now is a truly unique and utterly practical approach to creating a truly functional aquatic ecosystem.

The idea of creating a terrestrial environment, filled with sedimented soil, botanical materials, and immersion-tolerant plants and grasses, and then slowly flooding it over time to recreate the flooded forest floors of South America, for example, is not only simple to do, it literally forces us as hobbyists to make mental shifts towards patience, observation, and accepting an entirely new set of aesthetics.

It's certainly not for everyone.

However, the idea of executing an aquarium by creating the entire environment, terrestrial and aquatic- is just too irresistible not to try at least once in your botanical-style aquarium "career"- so you really need to! With the release of NatureBase "Igapo" and "Varzea" substrates now only weeks away (damn, I've said that enough times, huh? I mean it this time! We're in the final stretch!), it'll be easier than ever to flood your own forest!


I actually think that I will ultimately start all of my tanks via this format. I really think that there is something very interesting with this approach, and I believe that it's going to continue to yield very interesting results as the years go by.

Okay, commercial teases aside, I've been giving a lot of thought to the way that I start my aquariums. The "down time" I have at home with these small tanks has go even me the opportunity to try stuff that I wouldn't usually in larger tanks. This is a really great thing for me, because even I have to get out of my "comfort zone" now and again!

Staring at natural aquatic habitats and trying to understand how they formed, why the formed, and what factors influence their ecology keep me constantly inspired. Studying the igapo of South America has given me real inspiration and ideas to try in order to create more unique, highly functional aquarium systems.

Here's the other idea I've been playing with not only at the moment, but for some time now:

In situ "curing" of wood and botanicals. Something that indeed, goes against our "typical" practice, and certainly is different than my more "conventional" approach of boiling leaves and pods, and curing wood in a separate container of water. Rather, just "rinse and drop!" Hardly precise. And rather at odds with even our own "conventions" and practices that we've touted here!

Yet, playing with this approach has given me some of my favorite tanks ever!

It takes time, and a willingness to wait and observe and open yourself up to a bit of a "mess" at the beginning- at least in the "conventional" aquarium sense. To me, it seems like by doing this, you're actually letting Nature do Her thing!

It's not revolutionary...However, it is "evolutionary" for me, in that it more completely embraces my philosophy of building up a microcosm from scratch in an aquarium. This approach might be the ultimate expression of that. Think about this: Why do we "cure" wood outside of our display aquariums?

Well, typically, it's because we don't want the silt, sediment, biofilms and fungal growth which inevitably appears on wood when we submerge it for the first time, in our tanks. We want leaves and botanicals to sink right to the bottom. Also, not everyone is fond of the tannins released during this process, too. And the other materials, which we (present company include) have historically referred to as "organic pollutants", are seen as "undesirable." 

So, why?

Yeah, when you really think about it, all of these materials and compounds are food to various organisms, right? And when we remove this stuff, we're essentially depriving someone along the food chain their sustenance, right?

Yeah, the growth and proliferation of organisms of all types will contribute not only to the biological stability of the system over the long haul, I believe that it'll form the basis of a literal "food web" in the aquarium. Allowing this to happen, despite our human impatience- or even our initial aversion to the looks of the process- enables us to truly embrace the function of Nature.

In Nature, terrestrial materials covered by water are the basis for almost every aquatic ecosystem. The processes of decomposition and colonization- and utilization- of these materials by an enormous variety of organisms- is truly what "powers" these ecosystems. 

It works exactly the same in an aquarium...If we let Nature do her work without excessive intervention.

I'm really having trouble grasping exactly what the problem is with this approach- other than the obscene amount of patience we have to deploy as hobbyists waiting for our tanks to settle in and be "just right" for fishes.  Is it just the look? Is it because we've always been told NOT to start aquariums this way? Maybe? I mean, the aquariums that we play with own our world are not exactly "conventional", right? So what should the way we establish them be?

Sure, you might want to monitor ammonia and nitrite during the early phases, but since you're not in any real hurry, this might be more for informational purposes, rather than an indicator of "when to start adding fishes."

Secret: I've seen the fastest, least scary "cycling times" occur in tanks when I've utilized this approach. I mean, you COULD add fishes as soon as your ammonia and nitrite are undetectable...usually a week or less, in my experience! You just might not see your fishes very often in those early days in that morass of murky water , biofilms, and "stuff!"

And of course, all of this process DOES take some time.  No escaping that.

Like, on the order of around 3-4 weeks or more before you'd likely want to add fishes. And, I get it. Many hobbyists would rather get their displays up and running and "populated" with fishes and such pretty quickly. A tank full of biofilms, fungal growth, and "stuff" from the wood and leaves is not going to get you there quickly.

Ahh...but that's the interesting part to me!

Sort of doing your "scape" dry, and filling the tank up with conditioned water, and allowing the biofilm growth and dirt and all of that good stuff to sort of "brew"  creates a veritable "soup" of biological possibilities. Of course, you can't add fishes anytime soon, right? 

However, what you end up with in this little chaotic, murky, and rather disorderly-looking display is the beginnings of a microcosm, which will "sort itself out" as time goes by. About the only thing you need to do is maybe exchange some water after a week or two, and then get on a regular small water exchange schedule., like you would with any aquarium.

Now, it's not totally "seat of the pants"..I do assist things just a bit.

I add bacteria, in the form of Purple Non Sulphur bacteria (PNS) via our product, "Culture", as these highly adaptable bacteria not only "work" with the nutrients and compounds present in the aquarium via the materials- they will help "kick start" the nitrogen cycle as well.

This is exactly what we envisioned this product to do- To compliment the botanical-style aquarium approach and facilitate the development of a rich microbiome with natural processes.

The reality of this approach to creating a botanical-style aquarium is that it is allowing Nature to do what She does best- to efficiently use what's available to Her- to assemble and maintain an ecosystem.

These are, in my mind, exercises in functionality. Doing things in a fundamentally different way, in order to create a more robust, diverse, and rich ecosystem within the aquarium.

I think that we'll continue to work on some of these approaches more; perhaps refine the process into more definable "steps" so that others can try to validate or improve upon my "techniques" with this stuff.

Remember, it's okay to make a mess sometimes. Something amazing and beautiful might just come of it!

Stay bold. Stay open minded. Stay experimental. Stay observant. Stay enthralled...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


November 24, 2020


Under cover...or all over? Meet the Karsts

Sound like a bad sitcom, huh?

Stay with me here...

Every once in a while, it's interesting to contemplate an aquatic habitat that we don't think about all that much in the hobby. Today, let's talk about one that's definitely a bit different than the ones we usually find ourselves working with.

Let's consider the habitats around the karsts!

The what?

The karsts.

"WTF is a 'karst', Fellman?

A karst is an area of land made up of limestone. Limestone, also known as chalk or calcium carbonate, is a soft rock that dissolves in water. This process produces geological features like ridges, towers, fissures, sinkholes and other characteristic landforms. Many of the world’s largest caves and underground rivers are located in karstlands.

Karstic terrain. Image by Jan Nyssen (used under CC BY-SA 4.0)

The porous limestone rock holds a lot of groundwater, ponds, and streams, sometimes located underground. And those cool  structures known as cenotes (closed basins)! Yeah, we'll revisit those some other time.

Karsts are characterised by the presence of caves, sink holes, dry valleys and "disappearing" streams. These landscapes are known for their groundwater flow and efficient drainage of surface water through a wide network of subterranean conduits, fractures and caves.

Karst are found throughout the world, including France, China, the Yucatán Peninsula; South America, and parts of the United States.

In typical karstic habitats, the water is very clear, becoming turbid after heavy rains. Flash floods occur several times during the rainy season. In this period the stream width increases, making available habitats to be colonized, called here "temporary stretches".

Are you thinking what I'm thinking? Yeah, these could be interesting aquarium subjects! 

Yeah. And since a bunch of 'em occur in South America, where some of our fave fishes come from...this could be really interesting!

A fascinating neotropical karst landscape is located in the São Francisco River basin, Minas Gerais State, in Brazil. The fish diversity in these waters is significant. One study that I stumbled upon identified 28 species distributed in 3 orders and 9 families in this one locale alone!

The pH values in the South American karst habitats I found studies on range from 6.3 to 8.2, and averaged around 7.2 (slightly alkaline). Water temperatures average around 75 degrees F ( 23.8C), conductivity averages .30mS/cm, and the ORP averages 178 mv. (lower than one might expect, right? In reef keeping, we shoot for around 300 mv, so...) It's thought that the low levels of ORP can be associated with environmental pollution and/or high concentrations of ions, which is consistent in waters with karstic origins.

(The Hanna pH/ORP players do it, yo!)

And these protected pools, streams and caves present highly unique habitats for fishes.

Caves? Did I say, caves? Yup. That's pretty interesting. Must be a very protective environment.


Of course, it's not all roses and unicorns in these caves!  The more-or-less permanent absence of light and limited food scarcity represent the most conspicuous ecological pressures posed on cave fauna.

We'll talk about those some other time. Lets focus on the protected streams and pools.

What kinds of fishes do you find in them?


(The "lovely" Hemmigrammus marginatus!)

Characins, like Astyanax fasciatus, Hemigrammus marginatus, Hyphessobrycon santae, and Serrapinnus piaba were all found in this one location in Brazil! Cichlids were represented with the well-known Geophagus brasiliensis, and Loricariids with Hypostomus lima. Other catfishes, such as Pimelodella lateristriga and Hoplias malabaricus were also found there. And lesser appreciated (in the aquarium world, at least) Characidium sp. are also found in the habitat.

The much-loved Geophagus brasiliensis! (Image by Cezary Porycki, used under CC BY 3.0)

Siluriformes (catfishes) are considered by ichthyologists to be the most common fish group showing the traits required for cave dwelling, and they're considered "pre-adapted" to the subterranean habitat because of their nocturnal habits, electronic orientation abilities, and omnivorous or generalist carnivorous diet.

It will come as no surprise to dedicated readers of "The Tint" to discover that the surrounding terrestrial habitat has a profound influence on the species richness of the fishes found in these locales!

Studies determined that the percentage of "channel canopy cover "has the strongest effect on fish assemblages and is related to the percentage of organic matter in the streambed.  Greater density of riparian vegetation is correlated by field studies to have a profound influence on fish community composition.

Ichthyologists have found that the canopy cover increased stream channel shade (oaky, that's kind of a no-brainer, right?), enhancing habitat use by certain fish groups. Light reduction also lowers what ecologists call "primary production" which decreases the density of algae-consuming species . Ichthyhologists  working on karst pools determined that "roots, arboreal and aquatic vegetation positively affected the species diversity of fish assemblages."

Another case of fish following the food, right?

Now, cave communities are usually dependent upon allochthonous organic matter that may enter the subterranean environment carried by different agents (wind, percolation, falling into the water, current, etc.). 

Wood and organic material substrates are significantly less abundant in the subterranean karst habitats who compared with surface sites. Ecologists feel that the presence of wood in rivers can potentially affect the biodiversity of aquatic ecosystems in many different ways. Wood is considered to be an important nutrient source for aquatic insects. And we all know how fishes feel about aquatic insects, right? 

Of course, this food for the insects is a relevant factor regarding the trophic structure and productivity in aquatic food webs! Cave environments  represent what ecologists call ‘harsh’ oligotrophic habitats that may prevent the formation of  populations sufficient to support fishes. Rotifers are quite common in these habitats, and no doubt form a substantial part of the diets of smaller fishes. Copepods were the next most abundant food items in one study I read.


Again, the food webs area primary contributor to the suitability of a given habitat for fishes! It's thought that permanent dark passages in caves may act as ‘filters’, selecting fish species with the necessary attributes to move into and exploit the food resources present in them. It is  thought by scientists that the presence of subterranean spaces in the karst habitats is responsible for shaping the fish community, typically favoring nocturnal and small-sized species.

So, from an aquarist's perspective, karstic habitats should be pretty easy to replicate in the aquarium, right? Lots of smooth stone and sand, with a scattering of leaves and a few branches. This is one instance where I'd tell you to use activated carbon or other chemical media, to keep the water more or less clear. I mean, in soem habitats, it's crystal clear! Check out this video by our pal, Tai Strietman, of a karstic river in Mato Grosso do Sul, Brazil. Look at the current in that sucker!  I think I now have a freshwater application for my Vortech MP10 pumps!

(Yeah, we'll have to have Tai back on to talk more about this habitat! He talked about his visits to them in his last visit to "The Tint" podcast.)

Lots of epiphytic algal growth, some broken up leaves, aggregations of rocks...sand...I mean, this is like aquarist paradise! You can pretty much use every trick in the book and still come up with a reasonably faithful biopic representation- functionally aesthetic, no less! And, for some of you, not to have to deal with super acidic water and dark tint could be a real win, huh?

I hope you are at least intrigued by this unique habitat Obviously, in a brief blog like this, we can only touch on the most cursory stuff. As I mention al the time, you CAN find out information about this stuff online and elsewhere- just not really in the aquarium hobby realm. You'll need to dig deeper. Scholarly articles/research papers are treasure troves of information about all of these unique habitats that we talk about here. Don't be intimidated by the technical stuff in these papers.

There's so much amazing stuff in them that it's well worth the read!

We'll be talking more about this unique habitat, for sure!

Stay curious. Stay resourceful. Stay intrigued. Stay creative...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


November 23, 2020


The usual suspects? A simple case study for doing "common" in an "uncommon" way!

Periodically, I receive "I would love to hear your thoughts about this..." kind of emails from our readers/listeners, and almost all of them are really good! Sometimes, they touch on some ideas which really get me riled up. (maybe that's the intent, lol?)

Here's one that has come up a few times lately:

There is some perception that, as a group, we seem to think that we somehow have to create our aquariums for the most exotic, unique, and otherwise "Instagram-sexy" fishes in order for our work to be taken seriously by all the "cool kids." 

Well, this generated a huge WTF?! from me!

Like, is this really a thing?

Apparently, it is...Because no less than 4 different hobbyists brought this one to my the last 2 months alone!

And, doing a bit of research, I did see some evidence of this mindset percolating out there online.

So, what's my take on this?

Well, rather than giving the hobby culture an apparently well-deserved whack upside the head, let's try to be a bit more positive and think about some cool tanks that you could do for so-called "common" fishes.

I'll start with the most "common" fish you can get- the beloved Zebra Danio, Danio rerio.

As a kid, I think one of the most memorable sights in my first aquarium, complete with blue gravel and plastic plants, was my group of 8 Zebra Danios  (Danio rerio) racing at high speed around the tank in a furious fashion, as if they had to get somewhere in a big freaking hurry...only to reverse course, and do it all again. I've never forgotten how much I liked the Zebras- or almost every other Danio species kept in the aquarium. 

And the amazing thing about this fish is that it's probably THE most bulletproof species you can keep. In fact, I recall reading somewhere that it's "tolerated temperature range" based on wild type localities is from 76.2 – 101.5°F (24.6 – 38.6°C). I mean, if THAT isn't a broad range, nothing is! And it tolerates water with a pH from 6.0-8.0.

Yeah, these guys are hardly what you'd call "fussy" fish!

And you know me- once I hear that, I get these weird ideas like, "What if we mimic the conditions of the natural habitat of the fish? Would they do better? IS there an advantage somewhere?" I think like this for so many fishes, as if to shun the fact that 90% of what we keep in the aquarium these days has never seen a stream, pond, or river...

It's just..I don't know..irresistible to me to think about this kind of stuff! Taking the most common of common aquarium fishes and giving them "throwback" conditions; seeing if it somehow "awakens" something locked into their genetic code over eons...something...

I mean, it's kind of silly, I suppose...there are so many other things to do in the hobby...yet I can't help but wonder if we can learn something from replicating some aspects of their long-forgotten wild habitats...

And, in regards to the Zebra Danio, what's interesting to me is the habitats in which these fish are found. Typically, these fishes are found in Northern India, and this area is subjected to seasonal rainfall between the months of June and September due to the summer Monsoon, and the water levels and characteristics vary considerably at different times of the year. They are often found in inundated rice paddies and marginal pools, with silty, kind of turbid water with very little movement. During the dry times of the year, they spend their time in calm, shaded areas of streams, with rocky substrates. 

This is interesting, because it reminds me a bit of the Amazon igarape, although instead of rain forest, you've got rice paddies...

And, I've been playing with rice seeds, silted substrates, and turbid water lately! Hmmm...

So, my simple thought is...this fish seems to hang out in what we as hobbyists would think of us "less desirable" conditions for much of the year- the silty rice paddies...And only spends the dry season in the more permanent, less turbid streams. Why would this be? Is there some advantage? Like food, better substrates for breeding, protection? Why the turbid water? What does it bring to the fishes?

Would there be an advantage to keeping a fish like the Zebra in different conditions different times of the year, as in nature? Or simply in a tank representing one of the two habitats it's found in. Would you WANT or NEED to? I mean, the fish has been a captive-bred staple of the hobby for almost a century...but I can't help but wonder why these fishes live the way they do in the wild. What advantages do these habitats hold for the fish?

Would you get different behaviors, colors, health, spawning out of the fish by doing this "seasonal transition"..? Using a very fine sand substrate, maybe mixed in with some mud or something similar to replicate the rice paddies, with pump returns very gently angled at the bottom to simulate turbidity?


Again, why, you ask?

My answer? I just think it could be kind of cool. Weird, but cool.

Am I the only one who imagines weird stuff like this? Maybe?

On second thought- don't answer that!

I know, the fish is bred by the billion in fish farms all over the world, as are many much sexier, domesticated strains of its relatives...but wouldn't it be interesting to see what happens when you "repatriate" these "common" fishes to an uncommon execution of their natural habitats? 

I think it would be. In fact, I'm certain that it would be!

Obviously, this isn't limited to the humble Zebra Danio.

You create unique habitats for a huge variety of readily-available fishes. Think about faves like the Harlequin Rasbora, Trigonostigma heteromorpha which is often kept in planted tanks. yet when was the last time you saw it as the "alpha fish" in a system designed to replicate its preferred natural habitat? 

 (dimly lit peat forest swamps, small tinted jungle tributaries filled with leaf litter, or Cryptocoryne-choked streams)? 


I played with this approach for just such species- the ubiquitous Neon Tetra, and found it not only rewarding and fascinating, but highly engaging for other hobbyists, too. Oh, and they spawned, as well!. You can really go to town with some of these types of habitats...even with a "Pantanal-type" simulation, in which I used a mix of terrestrial grasses, weeds, and even some dead pieces of roots to recreate the look, richness, and the function of this unique habitat.

It's an altogether "unconventional" aesthetic, and a most counter-intuitive aquarium, rich, sediment-laden, tinted and turbid. A relatively high-nutrient tank...One in which the fishes utterly thrived! Yeah, the most "pedestrian" fishes.


The ongoing experimentation, the mental shifts that we've asked you to make, the "norms" of botanical-style aquarium "practice" that we've pushed here for a few years- all will come together to make these types of experiments unique and enjoyable to a wide variety of hobbyists! 

You simply don't need to have the most exotic fishes around in a tank to create excitement... You can create excitement about the entire ecosystems from which these "common fishes" originate.

"Common." In an "uncommon" way.

Stay excited. Stay brave. Stay curious. Stay creative. Stay innovative. Stay patient...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


November 20, 2020


Chasing The GOAT...

GOAT- adj./ - Sports acronym for "Greatest Of All Time"

Let's appropriate it for our own little review here of the greatest fish inventions of all time....

Our hobby has undergone numerous changes over the generations. Technology, technique, education, and experience have all impacted the way we play with tropical fishes. Things change rapidly, and the equipment we use today has changed with the times as well...Sadly some has even disappeared. 

Yet, there are still some pieces of equipment that have defied this progression. They've evolved a bit, but they fundamentally haven't changed all that much...'cause they work!

Yeah- we still embrace low-tech wonders from the past that have transformed our hobby, while transcending time and even defying more modern technology. Clever, crafty, defiant, and yet, useful things that are the literal “tools of the trade.” A chef has his knives, a carpenter his tools…We have these beauties. Here's my tribute to the simple, elegant stuff.

Where would the modern aquarium hobby be without stuff like:

The nylon fish net-  Like, seriously, how else do you catch a damn fish? The concept has been around for millennia. The kind we use have changed a bit, but the idea is unchanged since like Biblical times, right?

I mean, there was a time in the hobby, many years ago, when all you could get were cotton fish nets. With shitty metal handles that rusted out quickly. Nasty, icky musty fish nets were somewhat common.Yes, the nylon fish net predates most of us, but it’s just one of those things we take for granted as having "always been around." Like frozen blood worms or decapsulated brine shrimp eggs! It was a huge advancement. 

Ironically, the wooden-framed nets are considered better quality than the twisted, coated wire ones. And then there are plastic ones, too. Yet, IMHO, low tech rules! The newer ones that supposedly “blend in the water” so that fish don’t see them seem like a good idea to me…But I don’t think I’ve ever heard of a time when a fish “didn’t see” the net as it’s coming after them, nylon, plastic, or otherwise. Well, thank goodness for quality fish nets, regardless.

The latest iteration of an awesome, high tech wonder tool..

Plastic airline tubing- This stuff is the "duct tape" of aquarium keeping! Who among us doesn't have a few feet of this stuff lying around? Answer- NO ONE!

I mean, yeah, lots of hobbyists use it for pumping air into aquariums, but its so much more versatile. We use it for things like creating drip acclimation lines (hardcore users start a little siphon and then tie a knot with it to start a slow drip). We use it even when we don't have an air pump. I’ve seen it used for tying stuff together, making extensions on plastic syringes to act as an ITFD (“improvised target feeding device”), and many other uses. A serious invention that’s stood the test of time!

Oh, and you can get it in silicone, too!

The culinary world has flour. We have...airline tubing. Yeah. We do.

The airstone-  Wooden, ceramic, or plastic, this invention dates back to the 1940’s-50’s, and has been a fixture in the aquarium hobby to this day. This humble piece of technology, simple though it may be, is a cornerstone of modern aquaristic practice. An easy, elegant way to deliver aeration to an aquarium, it’s been used for many decades with reliable efficiency.

Sure, some of the plastic and wooden airstones are prone to clogging from time to time, but the ceramic ones, which have changed very little (in like, half a century!) are pretty damn reliable. Weather you’re using them to aerate a tank, hatch brine shrimp, power a protein skimmer, or provide aeration in a temporary holding container, the airstone is without peer in the world of aquarium supplies!

Be it ever so humble...the airstone transformed the hobby. Still does.

The plastic "specimen container"- Omigod, this is like the standard-issue piece of fish equipment.  The ultimate in resistance to evolution, too.

It’s transcended everything from Goldfish-keeping to reef-keeping. You’ll find specimen containers being used at every level of the hobby, all over the world! I’ve used them to acclimate corals, treat sick fishes, hold baby guppies, hatch brine shrimp, mix salt, thaw out food, hatch killie eggs... I mean, there’s hardly a fish room task that the decidedly low-tech specimen container is not up for! I mean, it's a fucking plastic box.

Yet, the damn thing is totally "future proof", too, right?

Q-How does a plastic box to hold water ever become "obsolete?"

A- It can't.

I don’t think the design has changed in like 50 years! It's used for everything. I even remember an early reef experiment where I directed water flow into one from my reef tank, put an old light fixture above it, grew some Caulerpa inside, along with some sand and (I don’t recall why) snails-and let the water flow back into my reef. This was like 1985, and it was my crude attempt at an “algae scubber”, or perhaps- maybe- I was the one who invented the modern refugium..Yeah, that’s it!  I'm a visionary.

OK, in my head, anyways…(the modern refugium concept actually predated my crude idea by years…but a guy can have his delusions, right?). But it all started with this humble device!

Is the "specimen container" the greatest aquarium hobby invention of all time? I think there's a really strong case to be made for this!

Don't you dare call it a plastic box! It can be whatever you want it to be. A foundation for dreams, even.

The algae scraper- Woah…Freshwater, saltwater, brackish- whatever. Hobbyists of every age, experience, and generation have come to hate algae on the sides of our aquariums. It’s a nemesis like no other, "defiling" our tanks, frustrating us, and causing hobby havoc. I know people that literally left the aquairum hobby because of algae. It’s hated stuff in our world. A constant battle many of us must fight, right? We needed a weapon, and the hobby gods obliged us.

Along came the algae scraper..and the battle was joined. Originally, just a piece of sponge on a stick, the algae scraper has evolved radically from humble "stone axe" to high-tech, stainless-steel synthetic wonder weapon! You have plastic scraping blades for acrylic, razors, dense matrix synthetic plastics, and other types of scrapers of varying composition and effectiveness. We have ergonomic plastic handles, replaceable scraping surfaces…

And we even have the ultimate evolution- to the algae cleaning magnet, equipped with replaceable, high tech synthetic pads to both polish your outside surfaces while attacking this dreaded pestilence- all while keeping your hand dry! You can hold a beer in one hand, and scrape algae with the other. Is that progress, or what?

The stick may be gone, but the goal is the same: Cleaning viewing areas without getting our hands wet.

Seachem created the "iPad of Algae Scrapers!" The latest, most elegant version of the original low-tech aquarium maintenance device...

So there you have just a few of the most humble, yet useful tools of all time. I could literally go on for hours. Don't tempt me.

Sure, we have sophisticated electronic controllers, super-smart, Bluetooth-enabled LED lighting systems, high-tech DC pumps, dosers, and other complicated gadgets, many of which I couldn’t even figure out how to use (however, I'm sold on my "Smart ATO" top system…Progress can be scary, right?).

However, these simple throwbacks, derived from need and function, comprise part of the legacy of our hobby’s “greatest generation”- that time when if you needed something fast, you’d cobble it together, because there was no Amazon, online vendors or Google…Can you imagine, having to "DIY"stuff?

Oh, wait- we still do DIY…THAT hasn’t changed! The only difference is that these things end up in our Facebook news feed (“Look, I repurposed my toothbrush into a protein skimmer cleaner!” Like, whatever, bro)

Okay, I"m really going on and on here. That's my style, though, right?

I submit to you that few, if any aquarium writers of my generation have written columns heaping g adulation on plastic specimen containers and the joys of airline tubing- and none threw together a piece on said subjects at 5:30 AM PDT)!

I open myself up to the scrutiny of my peers for my choices (Shit, this makes espousing stuff like blackwater aquariums feel like child’s play), and challenge you to add to my humble tribute list.

What humble, generation-spanning aquarium inventions do you find indispensable, and still relevant?

I want know. Don’t be shy- it’s the chance to wax poetic about the relics from a gentler, kinder time, when frozen food still got freezer burn, everyone was awe-struck by that green Eheim tubing, and there was only one choice for water testing (a pool pH test kit)…We owe it to these devices to pay them tribute.

Hell, we owe it to our children, to pass this "tribal knowledge" on, so that future generations of hobbyists can appreciate the efforts of the nameless hobbyists who helped build our culture.

Ok, that was really poetic, huh?  So, just share with us what gadgets from the past you still use. Simple. Extra points for pics of old, repurposed gear, too!

As always, look at the past with pride, look at the future with hope, and look at the present on your iPad.😆

Stay reflective. Stay innovative. Stay creative. Stay grateful...And always...

Stay Wet.

Scott Fellman

Tannin Aquatics

November 19, 2020


Fueling the process...

Of almost all of the natural processes that we in the botanical-style aquarium movement embrace, the process of decomposition is pretty much the "foundational" one that impacts our systems.

Decomposition, to refresh your memory, is the process by which organic materials are broken down into more simple organic matter. For our purposes, we are primarily interested in the breakdown of plant matter, ie; botanicals and leaves. It is in part responsible for some of the unique habitats that we love so much-and an inspiration for some unique aquariums with previously unappreciated aesthetics!

When leaves enter tropical streams and other bodies of water, fungal colonization causes leaves to increase the nitrogen content of the water (because of fungal biomass), and the process of leaf maceration begins. This is considered by aquatic ecologists to be evidence of microbial colonization. 

There are many different stages in the process, starting with the leaching of materials from the cells of the botanicals during initial submersion, in which soluble carbon compounds are liberated in the process. A rapid release of phosphorus also accompanies this leaching.

Of course, the process ultimately leads to physical breakdown and/or fragmentation of the leaves and botanicals into smaller "pieces", which possess larger amounts of surface area for microbial attachment.  Extensive ecological studies done by scientists specifically in regard to leaf litter have yielded a lot of information about this process.

The fungi known as aquatic hyphomycetes produce enzymes which cause leaf maceration, and in as little as 2 to 3 weeks, as much as 15% of the decomposing leaf biomass in many aquatic habitats is "processed" by fungi, according to one study I found.

Fungi tend to colonize wood and botanical materials, because they offer them a lot of surface area to thrive and live out their life cycle. And cellulose, hemicellulose, and lignin- the major components of wood and botanical materials- are degraded by fungi which posses enzymes that can digest these materials! Fungi are regarded by biologists to be the dominant organisms associated with decaying leaves in streams, so this gives you some idea as to why we see them in our aquariums, right?

In aquairum work, we see fungal colonization on wood and leaves all the time. Most hobbyists will look on in sheer horror if they saw this extensive amount of fungal growth on their carefully selected, artistically arranged wood pieces! Yet, it's one of the most common, elegant, and beneficial processes that occurs in Nature!

Of course, fungal colonization of wood and botanicals is but one stage of a long process, which occurs in Nature and our aquariums. Of course, as hobbyists, once we see those first signs of this stuff, the majority of us tend to reach for the algae scraper or brush and remove as much of it as possible- immediately! And of course, this provides some "aesthetic relief" for some period of time- but it comes right back...because these materials will provide a continuous source of food and colonization sites for fungal growths! 

And the idea of "circumventing" this stuff is appealing to many, but the reality is that you're actually interrupting the process. Nature abhors a vacuum, and new growths will return to fill the void, thus prolonging the process.

Although decomposition is a continuous process, taking place over long periods of time, studies carried out by aquatic ecologists in tropical forests in Venezuela demonstrated that decomposition rates were really fast, with 50% of leaf mass loss in streams occurring in less than 10 days!

The ultimate result is the transformation of what ecologists call "coarse particulate organic matter" (C.P.O.M.) into "fine particulate organic matter" (F.P.O.M.), which may constitute an important food source for other organisms we call “deposit feeders” (aquatic animals that feed on small pieces of organic matter that have drifted down through the water and settled on the substrate) and “filter feeders” (animals that feed by straining suspended organic matter and small food particles from water).

And yeah, insect larvae, fishes and shrimp help with this process by grazing among or feeding directly upon the decomposing botanical materials...We've talked about that quite recently, right?  So-called "shredder" invertebrates  (shrimps, etc.) are also involved in the physical aspects of leaf litter breakdown.

There's a lot of supplemental food production that goes on in leaf litter beds and other aggregations of decomposing botanical materials. It's yet another reason why we feel that aquariums fostering significant beds of leaves and botanicals offer many advantages for the fishes which reside in them! 

I have personally experienced this time and time again, by setting up botanical-style systems for the expressed purpose of providing supplemental food for the resident fishes. I've done this with adult fishes, and I've actually "reared" (well, Nature dod the work) many fish fry to maturity by setting them up in heavy botanical-stocked systems with little to no supplemental feeding. The fishes feed on the fungal growths and biofilms, as well as the organisms which are associated with them...just like in Nature.

The biggest allies we have in the process of decomposition of our botanicals in the aquarium are microbes (bacteria, fungi, and protozoa, specifically). Ecologists will tell you that during the early decay phase of botanicals/leaves, the leaching of water-soluble substances plays a key role in the loss of the physical  mass of these materials.

Alteration of the botanicals is done chemically via this microbial action; ultimately, the components of the botanicals/leaves (lignin, cellulose, etc.) are broken down near completely. In aquatic environments, photosynthetic production of oxygen ceases in plants, and organic matter and nutrients are released back into the aquatic environment.

All of these organisms work together- in essence, supporting each other via the processes which they engage in.

Fungal colonization facilitates the access of invertebrates to the energy trapped in deciduous leaves and other botanical materials found in tropical streams. Bacteria and fungi that decompose decaying plant material in turn consume dissolved oxygen for respiration during the process.


Of course, if you intervene by removing stuff- or, more commonly- by adding too much stuff in too short a period of time- bad things can happen.

This is why adding too much botanical material too rapidly to an aquarium can create problems for the fishes! A rapid decrease in dissolved oxygen in a small body of water can be disastrous; or, at the very least, leave fishes gasping at the surface! And of course, that's why we tell you to deploy massive patience and to go slowly when adding botanicals to an established aquarium...

And, as we discussed yesterday, the processes of decomposition and utilization of dissolved organic carbon from botnanical materials keep the water quality high, even in a closed aquarium with a ton of botanical materials breaking down!

It's thought by ecologists that the dissolved organic carbon is used as a "substrate" for microbial growth- thusly lowering the concentration of dissolved organic carbon in the water, and transferring energy from decomposing leaves and other materials to other trophic levels (defined as "hierarchical levels in an ecosystem, comprising organisms that share the same function in the food chain and the same nutritional relationship to the primary sources of energy.").


Now, I've played with the idea of "curing" wood directly in the aquarium, as opposed to doing it in a separate container many times, too. Now, I can't say that this would be everyone's cup of tea, as it creates a very "disturbing" look for many hobbyists! Aesthetics aside, I personally don't see a problem with breaking in a new, fishless aquarium by "curing"  the wood and such

in situ.

You just need to be super patient. You need to wait until the fugal growths peak and subside substantially. You need to keep your hands off and just...wait. So what advantage would such a practice bring? For one thing, you'd have a well-established cycle of microbial colonization, biological succession, breakdown and ultimately, decomposition before fishes are ever present.

You just have to look at the process as the beginning of a long, continuous journey, one that can take your aquarium to all sorts of amazing places if you[re incredibly patient, diligent, make the effort to understand what's happening.

You need to have faith. Faith in process. Faith in your own skills and patience.


Faith in Nature.


And process.

It's all about how the natural materials that we play with fuel the process of establishing, growing, and maintaining a closed ecosystem in our aquaria. Knowing that the turbid, biofilm-and-fungal-growth-filled aquarium that you've recently set up will evolve over time to a rich, diverse, biologically stable microcosm.


I think it's a sort of exciting frontier. The idea of "throwing it all together" and letting Nature sort it out isn't laziness. It isn't some crazy, alternative approach, either. It's a slightly different take on what hobbyists have been doing for generations. The reality is that it's simply a way to create a very dynamic ecosystem by powering up things immediately. Taking a longer, less aesthetically conventional road. An approach that can unlock so many secrets of Nature to so many hobbyists.

And it's really as much of a mental shift as it is anything else- like so much of what we do with botanical-style aquarium systems. The willingness of us to really look to Nature as more than just an inspiration for making cool-looking aquariums. Rather, an approach which understands that our botanical-style aquariums require  us to step back and observe what happens in wild aquatic habitats, and realizing that the same processes occur in our aquariums.

An understanding that "intervening" and "editing" the process by removing "undesirable" life forms is actually interfering with the development of a dynamic ecosystem.

Please consider such an approach. Please consider embracing the process of letting Nature do what she does, with the organisms which have evolved over eons to take advantage of the resources available to them. Understand how botanicals and wood "fuel" the process.

Stay diligent. Stay patient. Sty observant. Stay engaged...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


November 18, 2020


Explaining the swamp...

swamp: /swämp/ noun- An area of low-lying, uncultivated ground where water collects; a bog or marsh.

It's been a while since we've taken a more detailed look at a wild habitat, to get some insights in how it formed, what it's influences are, and how we can use this information to create aquariums which seek to replicate their form and function. So today, let's return to the swamps! Well, not just any old swamps- let's check out the peat swamps of Borneo! 

The island of Borneo is widely known as one of the most biodiverse ecosystems on earth, and the peat swamp forests there cover around 12% of the land in Southeast Asia! Peat swamp forests are a form of tropical forest in which very saturated soils (called "histosols" by geologists) inhibit the decomposition of organic materials, such as leaves and other parts of trees and forest vegetation, which leads to the formation over time of peat.

In areas with poor drainage, peat can accumulate over long periods of time until it rises above normal groundwater levels, which creates raised bogs, known to ecologists as "ombrogenous" bogs, which are fed only by rain, and thus have their own water table. The peat retains water via capillary action. These bogs can be as much as 60 feet (20 meters) deep(!), and are largely deficient in nutrients because of the lack of input of mineral input. The leaching of organic compounds from the peat causes the water contained in these bogs to be extremely acidic (like pH4 or lower!).

These "omborgoenous" peat swamps can develop in in areas between rivers in locales with year-round rainfall, as well. They're fascinating structures, home to an enormous diversity of life. Here's where it gets interesting to us fish geeks:

Studies have shown that approximately 219 species of fishes have been found in peat swamps, with approximately 80 of these species restricted to this habitat alone! And 31 are what are known as "point endemic" species, found only in single locations!

That's a LOT of species in a very unique habitat, huh?

 (image by Marcel Silvius)


Some scientists suggest that the conditions in peat swamps have favored the evolution of smaller, specialized fish species, and that each area of peat swamp could support its own  group of endemic species. This is interesting and important...Some species (17 have been identified at the moment) from these habitats are classified as vulnerable, endangered, or critically endangered.

In fact, the environments themselves are endangered...and humankind's encroachment, exploitation, and destruction of these habitats is a very dangerous problem for our planet's existence.

During the wet season, the peat swamps are inundated with water, which slows down the aerobic decomposition which occurs in the substrate- conditions which facilitate the formation of peat. During the dry season, the water levels in the swamps decrease, exposing a significant amount of peat to the air (which leads to decomposition and the release of CO2 into the atmosphere. This is exacerbated  by human intervention, such as slash and burn agriculture, etc.

We all know what that means.

Sadly, these vast swamplands are not well understood, and often are under appreciated in the nations in which they are found, treated like "wastelands", which need to be converted to other human-important uses. This has resulted in their rapid disappearance and an increasing in fires, logging, and conversion to agricultural and industrial uses.


Scientists on the front line of studying ecological dangers are concerned about this, because of the huge quantity of carbon that these swamplands store and potential release into the atmosphere. It's thought that as much as 3% of the total global emissions of CO2 can come from these habitats if they are destroyed- sparking a huge amount of concern and urgency to understand their impact as carbon stores.

And there are several types of well-studied peat types found in these swamps, varying by composition, based upon the materials found in the locales, and the amount of water present in the peat.


There's so much more than just peat and water in these habitats, and much more to study.

These are precious environments.

They require us to understand, explore, and preserve them. As aquarists, we can do our part by attempting to replicate these habitats in our aquariums, and to breed the species which come to the hobby from these habitats. Yeah, not only will our work help us to get a better understanding of the ecosystem, it will (if we're lucky and diligent) relieve some of the pressures on these vulnerable wild populations.


Species from the genera Sphaerichthys, Desmopuntius, Rasbora, Betta, and Channa are well-represented in these habitats.

Average water depth in these swamp habitats ranges from about 1/2" to as much as 3 feet (approx. 0.1 meters to 0.9 meters).  Researchers have found that these peat swamp fish communities are typically more species rich in habitats which offered higher levels of dissolved oxygen, interesting because we tend to think of swamp fish as being found typically in low oxygen environments, right?

That being said, there are plenty of fishes which have evolved to thrive in these habitats. For example, Betta hendra, one of the betta species, is only known to be found in the Sebangau forest! These are also specially adapted for life in the peat-swamp environment, with its lower dissolved oxygen levels. According to Fish Base, it's found in Found in, "...peat swamps with depth of about 5 to 50 cm and with no water current. The water was shaded by trees and bushes. Collected among the aquatic and marsh plants..."

(A great pic of B. hendra by our friend, Sumer TIwari)

Another gem from my research about dissolved oxygen levels and their impact on fish populations:

"Forest pools and canals in these regions have consistently lower dissolved oxygen levels the rivers and streams in the region do. This is probably due to the inherent nature ofthe aquatic habitat in peat swamp forests, where DO levels are kept low due to the high amount of tannins in the water (from the high organic matter content of the peat), with the accumulation of decaying organic matter depleting DO levels.

Additionally, there is low or no water flow (especially in the pools) which further ensure low levels of DO regardless of the lower surface temperatures of forest water bodies(Yule & Gomez 2009). Low concentrations of DO can make water uninhabitable for certain fish species, therefore the forest is likely to be a more challenging environment for fish survival."

Did you see the part about the tannins keeping dissolved oxygen levels lower? That's the first time I've heard that correlation made. Although, the next sentence clarified it for me, when it touched on the high level of organic matter depleting dissolved oxygen levels. So, my thinking is that the tannin is the result of the organic matter, but the organic matter itself is responsible for the lower oxygen levels.

This makes perfect sense, right?

We all know by now that too much botanical material added to the water in your aquarium in a short time period can result in depleted oxygen levels, leaving fishes gasping at the surface! If there is one "common botanical-style aquarium disaster trigger", that would be it. See- that happens in Nature happens in our aquariums. You can push it, but you can't hide from the consequences of trying to beat Nature's rules!

Interestingly, our captive aquariums might function in a very similar manner to the wild ecosystems.

The water of the peat swamps is very high in dissolved organic carbon, and it's thought by ecologists that the dissolved organic carbon is used as a substrate for microbial growth- thusly lowering the concentration of dissolved organic carbon in the water, and transferring energy from decomposing leaves and other materials to other trophic levels (defined as "hierarchical levels in an ecosystem, comprising organisms that share the same function in the food chain and the same nutritional relationship to the primary sources of energy.").

This would explain how tropical peat swamps support diverse, abundant flora and fauna despite incredibly low nutrient levels and lack of rapid leaf litter cycling, such as that which occurs in other types of tropical rainforests.

So, with some of this information in our grasp, how can we interpret it for use in our aquarium work? Now, sure, I could easily devote an entire piece to how you can recreate this habitat in your aquarium from a "functionally aesthetic" perspective- and we will. However, I'm not going to sell it short by just sort of touching on it here with a laundry list of,  "Use this botanical!", or similar. Let's just touch on one aspect- what I feel is the most important, and then we can cover the rest of this stuff in future piece.

Personally, I believe that we'd be both wise- and challenged- to attempt to replicate the peaty soils of the swamps. I think that it's the whole game here.

Now, many of us have mixed feelings about utilizing peat in our aquariums; however, there ARE some sources of sustainably-harvested peat available, but you'll have to do your homework to find them. We've covered this conundrum a couple of years back right here in "The Tint."

Are there alternatives? 

Well, sure. I think so.


In peat swamps, the peat layers may be well in excess of  3 feet (1m) deep. The floodplain forests are found along rivers, streams, coasts, and lakes. The seasonal flooding inundating the forests for short periods leads to an influx of sediment and mineral enrichment during high water periods. 

These soils are best replicated by using "non-traditional" substrates, like...coconut-based materials, finely-crushed botanicals, mud, sediments, etc...

(If you're thinking that we should come out with a "NatureBase" substrate inspired by this habitat, your correct! I've already formulated a version, and have been testing it for some time. We'll definitely release it as a "limited release" substrate in the coming months! 

There are some characteristics of these soils which will make them challenging in aquariums. For one thing, the physical characteristics of these materials will make them "behave differently" in water than traditional sands and other aquarium substrates. Peat, in its natural state, contains excessive amounts of water and is not exactly "sturdy" like sand or gravel because of its high permeability and has very low shear strength. And of course, it has a really low pH.

If we're trying to replicate the habitat as faithfully as possible, we'd want to use reverse osmosis/deionized water, or water with minimal carbonate hardness, and a soil with properties similar to peat. This could be challenging to manage for many hobbyists, because of the resulting pH. Not impossible- simply challenging.

We need to create a biological support web that is similar to that found in Nature, and that involves bacteria. We have a product, "Culture", which contains Purple Non Sulphur bacteria, which are extremely adaptive to low pH environments. We believe that this will make management of such systems a bit easier than it has been for hobbyists in years past.

Now, one thing to consider, of course, is that the fishes which reside in this habitat are intimately linked to it, and I think you'd do well to study the overall habitat. I could go on an on about each fish species, etc., but I think there are way better sources for that than I. What we need to discuss is really how to recreate the habitat more faithfully.

I also think that the aquarium configuration is important. I'd go with a smaller aquarium, depending upon the species you're wanting to keep, to create a very tightly controlled, cohesive environment. I'd look for a shallow, wide "footprint" for such an aquarium. 

I don't presume to be an expert on planted aquariums, but I do know that some species, such as Cryptocoryne, are found extensively in these environments, and would be the natural and easy choice for plants in such an aquarium. 


Filtration would be best accomplished with a canister or external power filter with gentle return flow, as water movement is minimal in these swamps. Plus, with a mix of rather buoyant substrate materials, you'd probably want to limit the heavy flow to keep them from blowing all over your tank!

I'd plant fairly densely, and intersperse lots of botanicals, to replicate some of the materials found in these swamps.

Perhaps you'd even want to include some palm fronds?

The maintenance of this aquarium would be no different than any of the Amazonian biotopes that we discuss so frequently here. Common sense water quality management, and regular water changes would go a long way towards maintaining a healthy environment for your little swamp!

Let's sort of leave it there, as we can go into much more aquarium-specific ideas on the recreation of this unique habitat in another blog post.

I hope that we've not only given you a few new insights on the peat swamps, but more important, inspired you to do further research on them. There is so much more than "tinted, low pH water" to the recreation of one of these habitats. It's going to require a lot of research and work to understand the unique dynamics of these fascinating ecosystems, and how to recreate them functionally in our home aquariums.

Let's roll up our sleeves and get to work!

Stay inspired. Stay creative. Stay observant. Stay brave...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


November 16, 2020


Embracing the "natural" part of Nature...Rebellion? Or philosophy?

It's interesting and gratifying that we receive so many questions from fellow hobbyists each day. And more and more, we're receiving questions about how our philosophy and approach to aquarium keeping has evolved. It does make me think about this stuff...

Sometimes, I have to re-examine my own thinking, and that of my fellow hobbyists. Other times, I have to actually appreciate the way things are going in the aquarium world, and how we arrived at the mindset we have.

Today's piece is about the latter...

WARNING: You may not like what I have to say. You may strongly disagree, think I'm a blowhard, or tell me I'm completely off. That's okay. This is my OPINION. And, because I've been asked about it so much, I'll share it with you here. If you disagree- or agree- I'd certainly love to hear your views.

One of the interesting things I've noticed in recent months is a slight mindset shift which appreciates things as they are in our aquariums. A sort of acceptance of natural processes and an appreciation for what they mean, what they are, and how/why they appear. A desire to understand, rather than fear, and a mindset which causes us to appreciate things, and question them-rather than loathe them outright. 

And we're seeing more and more hobbyists sort of question why "x" is seen as so bad within the hobby culture, rather than appreciating Nature's functions and processes.

Case in point: I saw a social media post the other day from a hobbyist questioning in a very direct way why we collectively freak out about stuff like algae in our aquariums. It made me feel good to see this from someone else, because as our long-suffering readers and listeners to "The Tint" know, we've been pushing this philosophy and mindset shift towards accepting Nature as it is- not the way we want it to be- for over five years.

It was literally the first mention I've seen of this by anyone else, and it was nice to see. Even more gratifying was to see all of the follow up comments! The "Hell yeah!"  and "Amen, brother!" types. This mindset is really starting to trickle into our hobby consciousness.

How refreshing!

When you look it it objectively, a sort of cottage industry within the aquarium hobby has been erected over the years to address our fears and to cater to our desire to eliminate the things which insult our ingrained aesthetics. Hobbyists spend a small fortune on algicides, water clarifiers, and all matter of stuff to edit out the "undesirable" parts of Nature. 

Algae. Biofilms. Sediment. Detritus.

The big problem, is that we as a hobby have for generations, set "rules" and "standards" that tend to force a lot of aquarists to conform to them, without question. To question or ruminate on contrary ideas or viewpoints has, for a long time, opened up those who dared to a lot of criticism, or even ridicule.

When we cam on the scene in 2015, there was a realization that this was not only counterproductive- but it was stifling any innovation that went against the grain, and deterring hobbyists from acting upon their curiosity. And that was a large part of the reason why we came on with such a heady "manifesto"; a sort of contrarian view about embracing Nature in our aquariums. 

We spoke- and continue to speak-our truth, in the hope that it will inspire our fellow hobbyists to speak their own. We wanted to provide a literal "safe space" for unusual approaches, contrarian ideas, and bold experiments. It's not about rebellion for the sake of being "in your face"- it's about literally "walking the walk" and putting ideas out there.

I hope it doesn't come across as arrogant. It probably sounds that way, I guess. Yet, the point here is that we are just a tiny, tiny part of the change in thinking that's taking place. Hobbyists are arriving at this conclusion on their own in greta numbers.

I believe that aquarists are wildly curious about the natural world, but that they tend to "overcomplicate" what is unknown, not well understood, or outside of the lines of "conventional aquarium aesthetics and practices"-and literally "polish out" the true beauty of Nature in the process-often ascribing "rules" and "standards" for how our interpretations of Nature must look. 

This is readily apparent in the competition aquascaping world, and other places where specific, human-imposed aesthetic standards are valued above all else. A world in which any deviation from these standards is seen as "reckless", "sloppy", "undisciplined", or just plain "shitty" ( actual words from hobbyists we've heard over the years...) Comparisons are made of many of these aquairums to Nature, yet, other than the fact that they contain live organisms, most of the tanks that are celebrated by a whole lot of hobbyists fall way short of "Nature", even by their own critical standards!

It's kind of funny to me.

What about celebrating function? What about celebrating sustainability, function over the long term? Those are important things, yet in our "visual-centric" hobby, these are seldom touched on as often as just the superficial appearance of stuff. I mean, we should- but that's only part of the equation.

What caused this mindset to saturate everything?

In my opinion, the misappropriation of the word "Nature" within the hobby has led us to this point. Specific aesthetics of Nature are met with high praise. The stuff which goes agains the "rules" is dismissed out of hand, categorized as "dangerous", undisciplined, etc.

And personally, I feel that's why large parts (not ALL, of course) of the freshwater aquarium hobby have been in a sort of "stagnation" for a couple of decades, a position that definitely opens up me and some of my colleagues to a lot of criticisms. However, they're totally worth enduring, because they leave no doubt about where we stand. And quite frankly, I think I'm correct in this thinking. 

Many hobbyists simply don't want to let go of "traditional" ways of thinking about and approaching aquarium work. Now, sure, you have unbreakable natural rules, like those which govern processes like the nitrogen cycle. You can't get around those. However, the way we interpret and approach many of the things which happen in our aquariums is all up for review, IMHO. And a lot of hobbyists are ready to do this.


At the risk of being a bit weird for quoting myself, I think I expressed a good part of our philosophy here at Tannin in this passage from a piece I wrote a couple of years back:

"Suffice it to say, there are NO rules in rediscovering the unfiltered art beneath the surface. Our "movement" believes in representing Nature as it exists in both form and function, without removing the very attributes of randomness and resulting function that make it so amazing.

We are utterly inspired by this.

We are about the preservation of biofilms, decomposition, and that "patina" of biocover that exists when terrestrial materials contact water. Understanding that these materials break down and influence the environment...and that this process doesn't always conform to our hobby interpretation of what is "beautiful." An appreciation of the ephemeral, the transitional."

This is quite contrary to the mindset of perfectly manicured aquariums, which remain "static" in appearance- beautiful though they are- because they're enslaved by some human-imposed constructs and rules, which dictate what's "good" and what's not.

I say, enough off this bullshit.

It's time to study, understand, and embrace the "natural" part of Nature. IMHO, some of the only "rules" worth following and understanding are those imposed by Nature herself. Rules which have dictated the formation, evolution, and operation of aquatic environments for eons before humans came along to classify, identify, modify, and standardize.

We're not alone in our thinking on this.

And the cool thing that we've noticed within our community is that every aquarium pic that is shared  by our community, which incorporates botanical materials and other elements of Nature in "a more natural way" is studied, elevated..often celebrated- as a humble, but beautiful homage to of the genius of Nature in all of Her random glory. A contrast to what has been accepted for so many years in the aquarium world as the "correct" way. The only way.

We as a hobby seem to be finally loosening the shackles of this thinking and pushing beyond. You're not seeing nearly as many comments of the, "That's a dangerous approach" kind these days.

It makes sense.

I think that many hobbyists are simply "over-saturated" with this stuff. Overexposed to the constant imposition of this tired mindset. It's inescapable everywhere on social media, and it's served to "set the rules" which many hobbyist have for years felt they must embrace.

Not so much, these days. The cracks are opening up. It's becoming increasingly obvious that many hobbyists are simply tired of this stuff.

Tired of it.


In my own rebellious way, I can't help but think that part of this enthusiasm which our community has shown for this stuff is that many aquarium hobbyists in general have a bit of a "rebellious streak", too, and that maybe, just maybe- we're all a bit well, "over" the idea of the "rule-centric", mono-stylistic, overly dogmatic thinking that has dominated the aquascaping world for the better part of a decade.

Maybe it's time to look at Nature as an inspiration again- but to look at Nature as it exists- not trying to sanitize it; clean it up to meet our expectations of what an aquarium is "supposed to look like."

And by the same token, understanding that not every hobbyist wants to-or can-go to the other extreme-trying to validate every twig, rock, and plant in a given habitat, as if we're being "scored" by some higher power- a universal "quality assurance team"- which must certify that each and every rock and branch is, indeed from "The Rio Manacapuru in October", for example, or your work is just some sort of travesty.

Not that there is anything wrong with this pursuit, or that I take any issue with talented hobbyists who enjoy that route. I identify with them more than the "high concept" aquascape crowd for sure! I simply believe that there is a "middle ground" of sorts, where nature is the primary influence, and accepting it and attempting to replicate it "as it is" -becomes the goal.

That's where we operate. Inspired by Nature.  It's appearance AND its function.

It's entirely possible to accept the appearance of biofilms, "murky" water, algae, decomposing botanical materials, and how systems embracing them can be managed to take advantage of their benefits. You know, accepting them as supplemental food sources, "nurseries" for fry, and as interesting little ways to impart beneficial humic substances and dissolved organics into the water.

It starts by looking at Nature as an overall inspiration.

Wondering why the aquatic habitats we're looking at appear the way they do, and what processes create them. And rather than editing out the "undesirable" (by mainstream aquarium hobby standards) elements, we embrace as many of the elements as possible, try to figure out what benefits they bring, and how we can recreate them functionally in our closed aquarium systems.

The "different aesthetics" simply come along as "part of the package"- both in Nature and in the aquarium.

Please don't misunderstand me here.

I'm not attacking "the establishment" and saying that every perfectly manicured competition aquascape sucks. I'm not saying that if a tank doesn't have blackwater, biofilms, and brown leaves that it's "uninspired" or "fake" somehow. I'm not saying that we need to burn down the house and rebel against every aquarium "best practice" that we've created and utilized for generations.


I'm merely questioning the insanely high level of esteem which the broader aquascaping and general aquarium hobby world seems to attach to conforming to some rigid style, constantly replicating the work of others, and being rather close-minded to the work of Nature, and that of hobbyists who try truly different things in their tanks.


Doesn't it get a bit boring after a while? This metaphorical circle jerk?

I think it does.

And things are changing.

Some of the most amazing comments we receive after sharing underwater pics of the wild habitats of Amazonia and elsewhere are from hobbyists who, at first, thought that some of these pics were from someones' aquarium! In a few instances, some of the close ups of botanical-themed aquaria are virtually indistinguishable from wild scenes!

That says a lot. It shows how far we've come.

And we have farther to go still.

And we'll keep going there. Together.

I know some of this stuff was not pleasant to hear. I realize that many of you may strongly disagree with my viewpoint. Some of you may think I'm an arrogant a-hole. And that's okay. We sometimes need to get this stuff out there!

Stay true to yourself. Stay curious. Stay enthralled. Stay brave. Stay rebellious- when required...

And Stay Wet.


Scott Fellman

Tannin Aquatics 



November 14, 2020


Lessons learned as the waters recede...

As we've discussed many times, there are some remarkably compelling environments which occur in Nature when rain causes rivers to overflow, inundating the terrestrial environment, and transforming it into an aquatic ecosystem.

These transformational habitats become home to numerous species of fishes and other aquatic life forms as they migrate into the newly forged underwater biome. It's a dynamic habitat, ever-changing as the inundation period progresses.

The water level can rise as much as 10 meters (30 feet) in a given inundation cycle. Obviously, when you're talking about an influx of water of that magnitude, it's a significant event. And it impacts the terrestrial vegetation profoundly. The upper parts of the larger trees in the inundated forests remain above the flood water, while younger trees of the same species and the shrubs remain fully submerged up to a few months each year before the waters ultimately recede.

And that's where it gets really interesting!

We talk a lot about the leaves which fall off the trees into the water. What about those which remain on the trees during the seasonal flooding.

How do the trees and other vegetation survive this inundation?

I mean, while submerged, the leaves on these plants are exposed to a hypoxic (low or depleted oxygen ), or even anoxic (devoid of oxygen) environment. And yet, they remain intact. After an inundation period which can last several months, the leaves which remain on the trees appear to be capable of resuming their primary function. One study determined that, " least the majority of the leaves not shed at the beginning of the inundation remain functionally capable, at least when the water depth at which they remain does not exceed 1.5 m."

Ohh. That's cool!

And interestingly, there are other distinctions between what happens in the whitewater-inundated Várzea habitat, versus those which occur in the blackwater-inundated Igapo: Some of those in the Várzea are only lightly coated with sediment, while some in the Igapo are covered only by spicules (small skeletal elements) from freshwater sponges. (don't get me started on freshwater sponges! I mean, man...)

Interestingly, in a study of the leaves of around 20 different species of trees found in a Varzea habitat in Brazil revealed that they possess an epidermal surface structure that's similar to...wait for it...rice plants! Of course, rice plants grow partially submerged, right? This epidermal structure permits a film of air to adhere to the surface when the leaves are first submerged at the beginning of the aquatic phase.

Now, stick with me here. 

This is thought by scientists to be an adaptation by the leaves to allow them to survive underwater or periods of time. What this means is that gas exchange occurs between the water and air trapped in the leaves. Carbon dioxide can, under a sort of "partial pressure", enter the leaf structure, leave solution, and enter the leaf openings in the form of gas.

In short, the stomata (minute pores in the epidermis of the leaf or stem of a plant) are protected by heavy waxes, or by a covering of cells against infiltration by water. And the trapped air in these structures permits a low level of photosynthesis to occur under water in the presence of a sufficient light.

Okay, that's freakin' cool.

And yeah, as the waters recede, these trees and plants not only bounce back- they continue to grow and thrive. They've adapted to these seasonal cycles of inundation and desiccation, supporting the ebb and flow of life both above and below the water.

So, what are the implications for us as hobbyists?

For one thing, it means that some terrestrial plants are quite adaptable to submersion for short periods of time. Could this be worth experimenting with in aquaria? Like, doing the "Urban Igapo" thing, starting off with a terrestrial habitat, and flooding it with water for some brief period of time, while utilizing plants that appear to have a waxy coating on their leaves.


I mean, I could be way off here, but it's a starting point, right? Perhaps those with horticulture backgrounds, or simply houseplant lovers might have a lot more to add to this conversation. In the mean time, I think that this might be a good avenue to explore, huh?

A simple idea based on a hunch and an anecdotal observation from Nature, but a good rationale for the possibility for utilizing terrestrial houseplants in our aquarium experiment! It sort of reminds me of the admonitions that you see about that "aquarium plant" which you see at the "big-box" pet store that is really a terrestrial plant, and that it, "...won't survive long term underwater..."

Yeah, but it might survive the "short term" underwater, right?


We can use those types of crazy hobby culture "no-no's" as an impetus to explore possibilities...

It's stuff like that which keeps me fascinated. It's why I've been experimenting with various grass species in my "Urban Igapo" habitats, and have seen long-term survivability/viability in several species after sprouting, growing, and then being submerged for a period of time, and then continuing to survive as the water recedes. 

What's the lesson here?

Many trees, grasses, and plants can adapt to survive the inundation, and resume their growth when the terrestrial conditions return. Nature strikes a remarkable balance between two dramatically different habitats. The relationship between land and water is intimate, dynamic, and interwoven.

There's a lot to take away here.

These interesting points from scientific studies can fuel our own hobby-level aquarium work. And the experiments can be quite simple, and still yield impressive and interesting results!

We favor terrestrial plants- and grasses-grown from seed, to start the "cycle."

SO, those of you who are ready to downplay the significance of experimenting with this stuff because "people have done 'dry start' planted tanks for years" , take comfort in the fact that I recognize that, and acknowledge that we're taking a slightly different approach here, okay?

We all possess the "skill set" to explore this unique avenue, and to make interesting and useful observations that will contribute mightily to the body of knowledge of the captive representation of these habitats.

You just have to innovate, and be willing to do a little busy work. You can keep it incredibly simple, and just utilize a small tank. You must be patient, observant, and curious.

There are so many possibilities here...

As I mentioned in a piece back in 2019, it literally, "...could create an entirely new 'sub-hobby' within the aquatic hobby...not just biotope replication- biotope 'operation!' The idea of a '365 Dynamic Aquatic Display'- what we've dubbed the 'Urban Igapo'- has never been more approachable! And you can, as the name implies- recreate it in the comfort of your own home."

Did I just quote myself?


Damn, that was cool!

As always, turn to Nature as it really is for your examples, and study, replicate, and innovate from there.

Let's see some of your experiments. Let's venture out into some deeper water and new ideas. It's a big win for the aquarium hobby!

Stay innovative. Stay excited. Stay curious. Stay experimental. Stay observant. Stay diligent...

And Stay Wet.


Scott Fellman

Tannin Aquatics 




November 12, 2020


Transitional habitats...from the underwater perspective?

There is something extremely compelling about the water/land relationship that I just can't seem to get enough of, when it comes to aquariums. 

We're starting to see more and more aquariums representing the flooded forests, swamps, and wetlands from the underwater perspective. Lots of interesting work with seed pods, branches, and leaves. 

We've started to really push out the "Urban Igapo" idea of creating a "wet season/dry season" dynamic in our own aquariums, using terrestrial plants, soils, and other natural materials.

Although, I think we can and should go a little further with these types of representations. Compelling habitats, like wetlands and swamps are fascinating subjects for aquaria. And the irony is that we tend to represent these unique habitats primarily with paludariums and such in aquarium work. We tend not to focus totally in the underwater part, lol.

Now, wetlands in and of themselves are interesting habitats, and include such obsession-inducing ecological niches as mangrove swamps, varzea, and bogs! Wetlands may be saturated with water either seasonally or permanently, and  are home to aquatics AND terrestrial plants. They are among the most biologically diverse of all ecosystems- and as such, are a really fascinating subject for our aquarium work, right?

Of course, because there is a most intimate relationship between the water and the surrounding terrestrial environment, it's worth noting that there is a lot of inspiration out there. 

The water chemistry of wetland habitats is dependent upon the source of the water and the geological material which it flows through, such as the aforementioned peat swamps, bogs, or mangrove swamps. The soils support biological activity and diversity within the aquatic ecosystem, and provide not only a literal "foundation" for plant growth, but a zone in which various microorganisms, insects, and other life forms thrive, forming the basis of a food chain.

As mentioned previously, many are inundated year-round, although some wetlands are ephemeral in nature, such as the varzea in South America, or even some of those temporary pools you find in the plains of Africa, which are home to some of our favorite annual killifishes, such as Nothobranchius! We've talked about this before, right?

So, if you're thinking what I'm thinking...and I know that you are- the fact is, there are numerous ways to replicate these types of environments in the aquarium!

You can opt to construct something as faithful to the real thing as possible, really trying to be biologically correct- or you could go for something inspired by these habitats. I'm playing with something like that in my brackish water mangrove thicket tank...Mangroves are really great plants to play with in such an aquarium. Especially when we over-emphasize the underwater segment!


And of course, there are also those peat swamps from Southeast Asia, which are a very interesting and distinct ecological niche. With a little research, and use of the right plants and materials, faithful recreations of these habitats are totally achievable! And, as aquarists, it's fun to emphasize the underwater aspect.

And then, you have regions in South America, such as the Pantanal, in which many grasses and other plants create a very unique habitat. One that's begging for more representation in the hobby.

We've talked a lot about flooded forest floors and inundated meadows in the tropical regions of the world, specifically South America and Southeast Asia. Being terrestrial habitats, these forest floors are often covered with shrubs and grasses, many of which are not typically available in the aquarium hobby.

Grasses, such as Paspalum repens, a common species found in South America, and several other grasses, are quite abundant in these habitats, and are most resistant to prolonged submersion. Seeing a formerly terrestrial habitat transformed into an aquatic one is a moth-watering subject for many hobbyists to replicate in aquariums!

And we can do it with some grasses that are available to us.

Now, there are species of Paspalum which are available as seed in many parts f the world, particularly North America and Europe. You absolutely can grow these and utilize them for the "role" of  ("generic") "Panatanal grasses" or "forest grasse"s in your displays. Many of them are remarkably tolerant of submersion for brief periods of time! 

We as hobbyists can do a lot of work to help figure out which terrestrial plants can tolerate/grow/thrive under submerged or partially submerged conditions. Perhaps a more "realistic" (not in the hardcore "biotope aquarium contest" context, of course) avenue to explore in this regard?

And of course, there are trees, too. I've seen a few tanks beautifully replicate this habitat, both with natural branches/wood and synthetic ones (Beautiful, but, yuck. I know I'll hear it for this..bring on the hate mail...)

Speaking of trees...

I've got one tree for you to research...the dominant terrestrial plant in the South American flooded forests is Eugenia inundata... Don't think I'm not well underway in my (somewhat futile) efforts to see if we can secure fallen leaves or branches of THIS plant! You'll also find Iriartea setigera, Socratea exorrhiza, Mauritiella aculeata palms in these areas..

Get after it, guys...

(Mauritiella aculeata - Image by pixel too used under CC BY 2.0)

Like so many things from the Amazon, it's not easy (read that, damn near impossible) to secure botanical material from this region, so the proverbial "Don't hold your breath waiting for this" comes to mind! Oh, and the submerged grasses we see and drool over in those underwater pics from Mike Tucc and Ivan Mikolji of these habitats?

They're typically Paspalum repens and Oryza perennis.

And we DO have access to some species, such as Sedges and other riparian or semi-aquatic/bog plants from genera that are found in these regions, such as Papyrus (Cyperus), Acorus, Orzyas, etc. These are surprisingly popular plants in the hobby, and for the purpose of recreating one of these seasonally-inundated habitats, they're near perfect! 

Since many of these plants tolerate submersion for extended periods of time, they are of great interest to many of us for use in our aquariums. Of course, part of what interests me is that these are generally very hardy plants.

Even when they die off and decompose, they form a compelling niche in the underwater environment. A rich, diverse, and productive habitat.

There are numerous species more commonly available from commercial nurseries in North American and European nations, so creating realistic representations of these habitats in our aquariums is more attainable than ever! Acorus is my fave.

Now, with this in mind, there are also lots and lots of possibilities for creating unique aquatic displays with what I would call "aquatic analogs" of these grasses and shrubs. In other words, incorporating some true aquatics to replicate the "look" of the flooded forests using representative species. I mean, we are talking about the "underwater perspective", right?

I freely admit that this is a total "cheat"- but when you think about it, it's a pretty good method that can be employed if you want to represent the inundation period from the underwater perspective for the theme of your aquarium, and aren't able to secure or grow the terrestrial/semi-aquatic analogs to the species found in these habitats.

I know a few that could work!

I'm thinking about plants like Echinodorus tenellus, the "Pygmy Chain Sword", which grows in a most "grasslike" state, and certainly is representative of the grasses one might find on a flooded Panatanal or forest floor habitat in South America.

It's not hard to cultivate a little section of these plants in your representation of a flooded forest, and drop in a few leaves and botanicals, and achieve a relatively realistic-looking facsimile of the flooded grasslands from this underwater perspective.

Another great candidate that has a sort of "generic tropical terrestrial grasslike" appearance would be Cryptocoryne parva. This diminutive plant actually can be grown emerged, so for "semi-flooded" igapo or varzea biotope aquariums, it would be really adaptable! And when submerged, it bears strong resemblance to Paspalum or other tropical, submersion-resistant grasses. (It's the plant in the foreground in the below pic, BTW)

Geographic transgressions aside, it's an interesting subject for this purpose. 

I suppose the old fave, Sagittaria, could also be employed for this purpose, but some species can achieve a larger size and perhaps ultimately be not as realistic, so you'd need to choose carefully. More exotic, but readily available as tissue-cultured, would be the beautiful Lilaeopsis mauritiana, a beautiful  species often called "Micro Sword" for its appearance and size.

Yeah, a lot of aquatic plant candidates here.

And of course, since we're representing a flooded forest floor or meadow, with patchy growth over rich soil and leaves, you likely don't need to have the full-on green lawn that planted aquarists strive for so ardently!

A little bit of "open space" and some twigs, roots,  bark pieces, a few seed pods, and exposed substrate and you're well on your way to creating a remarkably cool tank! In fact, you can omit the plants altogether, and replicate the "late season" inundation, when most of the terrestrial vegetation has either went dormant or died off.

The idea of representing the terrestrial habitats during their submerged phase as the subject of your aquarium is really compelling. There's plenty of room for creativity, experimentation, and yes- breakthroughs.

Stay inspired. Stay curious. Stay creative. Stay excited...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

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