What our fishes eat...The wonder of food webs.

Yes, I admit that we talk about some rather obscure topics around here. Yet, many of these topics are actually pretty well known, and even well-understood by science. We just haven't consciously applied them to our aquarium work...yet.

One of the topics that we talk about a lot are food webs. To me, these are fascinating, fundamental constructs which can truly have important influence on our aquariums.

So, what exactly is a food web?


A food web is defined by aquatic ecologists as a series of "trophic connections" (ie; feeding and nutritional resources in a given habitat) among various species in an aquatic community. 

All food chains and webs have at least two or three of these trophic levels. Generally, there are a maximum of four trophic levels. Many consumers feed at more than one trophic level.

So, a trophic level in our case would go something like this: Leaf litter, bacteria/fungal growth, crustaceans...

In the wild aquatic habitats we love so much, food webs are vital to the organisms which live in them. They are an absolute model for ecological interdependencies and processes which encompass the relationship between the terrestrial and aquatic environments.

In many of the blackwater aquatic habitats that we're so obsessed with around here, like the Rio Negro, for example, studies by ecologists have determined that the main sources of autotrophic sources are the igapo, along with aquatic vegetation and various types of algae. (For reference, autotrophs are defined as organisms that produce complex organic compounds using carbon from simple substances, such as CO2, and using energy from light (photosynthesis) or inorganic chemical reactions.)

Hmm. examples would be phytoplankton!

Now, I was under the impression that phytoplankton was rather scarce in blackwater habitats. However, this indicates to scientists is that phytoplankton in blackwater trophic food webs might be more important than originally thought! 

Now, lets get back to algae and macrophytes for a minute. Most of these life forms enter into food webs in the region in the form of...wait for it...detritus! Yup, both fine and course particular organic matter are a main source of these materials. I suppose this explains why heavy accumulations of detritus and algal growth in aquaria go hand in hand, right? Detritus is "fuel" for life forms of many kinds.

In Amazonian blackwater rivers, studies have determined that the aquatic insect abundance is rather low, with most species concentrated in leaf litter and wood debris, which are important habitats.  Yet, here's how a food web looks in some blackwater habitats : Studies of blackwater fish assemblages indicated that many fishes feed primarily on burrowing midge larvae (chironomids, aka "Bloodworms" ) which feed mainly with organic matter derived from terrestrial plants!

And of course, allochtonous inputs (food items from outside of the ecosystem), like fruits, seeds, insects, and plant parts, are important food sources to many fishes.  Many midwater characins consume fruits and seeds of terrestrial plants, as well as terrestrial insects.

Insects in general are really important to fishes in blackwater ecosystems. In fact, it's been concluded that the the first link in the food web during the flooding of forests is terrestrial arthropods, which provide a highly important primary food for many fishes.

These systems are so intimately tied to the surrounding terrestrial environment. Even the permanent rivers have a strong, very predictable "seasonality", which  provides fruits, seeds, and other terrestrial-originated food resources for the fishes which reside in them. It's long been known by ecologists that rivers with predictable annual floods have a higher richness of fish species tied to this elevated rate of food produced by the surrounding forests.



And of course, fungal growths and bacterial biofilms are also extremely valuable as food sources for life forms at many levels, including fishes. The growth of these organisms is powered by...decomposing leaf litter! 

Sounds familiar, huh?

So, how does a leaf break down? It's a multi-stage process which helps liberate its constituent compounds for use in the overall ecosystem. And one that is vital to the construction of a food web.

The first step in the process is known as leaching, in which nutrients and organic compounds, such as sugars, potassium, and amino acids dissolve into the water and move into the soil.The next phase is a form of fragmentation, in which various organisms, from termites (in the terrestrial forests) to aquatic insects and shrimps (in the flooded forests) physically break down the leaves into smaller pieces. 

As the leaves become more fragmented, they provide more and more surfaces for bacteria and fungi to attach and grow upon, and more feeding opportunities for fishes!

Okay, okay, this is all very cool and hopefully, a bit interesting- but what are the implications for our aquariums? How can we apply lessons from wild aquatic habitats vis a vis food production to our tanks? 

This is one of the most interesting aspects of a botanical-style aquarium: We have the opportunity to create an aquatic microcosm which provides not only unique aesthetics- it provides nutrient processing, and to some degree, a self-generating population of creatures with nutritional value for our fishes, on a more-or-less continuous basis.

Incorporating botanical materials in our aquariums for the purpose of creating the foundation for biological activity is the starting point. Leaves, seed pods, twigs and the like are not only "attachment points" for bacterial biofilms and fungal growths to colonize, they are physical location for the sequestration of the resulting detritus, which serves as a food source for many organisms, including our fishes.

Think about it this way: Every botanical, every leaf, every piece of wood, every substrate material that we utilize in our aquariums is a potential component of food production!

The initial setup of your botanical-style aquarium will rather easily accomplish the task of facilitating the growth of said biofilms and fungal growths. There isn't all that much we have to do as aquarists to facilitate this but to simply add these materials to our tanks, and allow the appearance of these organisms to happen. 


You could add pure cultures of organisms such as Paramecium, Daphnia, species of copepods (like Cyclops), etc. to help "jump start" the process, and to add that "next trophic level" to your burgeoning food web. 

In a perfect world, you'd allow the tank to "run in" for a few weeks, or even months if you could handle it, before adding your fishes- to really let these organisms establish themselves. And regardless of how you allow the "biome" of your tank to establish itself, don't go crazy "editing" the process by fanatically removing every trace of detritus or fragmented botanicals.

When you do that, you're removing vital "links" in the food chain, which also provide the basis for the microbiome of our aquariums, along with important nutrient processing.

So, to facilitate these aquarium food webs, we need to avoid going crazy with the siphon hose! Simple as that, really!

Yeah, the idea of embracing the production of natural food sources in our aquariums is elegant, remarkable, and really not all that surprising. They will virtually spontaneously arise in botanical-style aquariums almost as a matter of course, with us not having to do too much to facilitate it.

It's something that we as a hobby haven't really put a lot of energy in to over the years. I mean, we have spectacular prepared foods, and our understanding of our fishes' nutritional needs is better than ever.

Yet, there is something tantalizing to me about the idea of our fishes being able to supplement what we feed. In particular, fry of fishes being able to sustain themselves or supplement their diets with what is produced inside the habitat we've created in our tanks!


A true gift from Nature. 

I think that we as botanical-style aquarium enthusiasts really have to get it into our heads that we are creating more than just an aesthetic display. We need to focus on the fact that we are creating functional microcosms for our fishes, complete with physical, environmental, and nutritional aspects.

Food production- supplementary or otherwise- is something that not only is possible in our tanks; it's inevitable.

I firmly believe that the idea of embracing the construction (or nurturing) of a "food web" within our aquariums goes hand-in-hand with the concept of the botanical-style aquarium. With the abundance of leaves and other botanical materials to "fuel" the fungal and microbial growth readily available, and the attentive husbandry and intellectual curiosity of the typical "tinter", the practical execution of such a concept is not too difficult to create.

We are truly positioned well to explore and further develop the concept of a "food web" in our own systems, and the potential benefits are enticing! 

Work the web- in your own aquarium!

Stay curious. Stay observant. Stay creative. Stay diligent. Stay open-minded...

And Stay Wet.


Scott Fellman

Tannin Aquatics 


Stuff we've been told to fear...

A couple of days back, I was chatting with a fellow hobbyist who wanted to jump in to something a bit different within the aquarium hobby, but was afraid of the possible consequences-both socially and in his aquariums. He feared criticism from "them", and that just froze him. I felt bad that he was so afraid of criticism from others should he question the "status quo" within the hobby.

Perhaps my story might be helpful to you if you're afraid of such criticisms. 

For generations, we've been told in the aquarium hobby that we need to be concerned about the appearance of all kinds of stuff in our tanks, like algae, detritus, and "biocover".

For some strange reason, we as a hobby group seems emphasize stuff like understanding some biological processes, like the nitrogen cycle, yet we've also been told to devote a lot of resources to siphoning, polishing, and scrubbing our tanks to near sterility.

It's a strange dichotomy.

I remember the first few botanical-style tanks I created, almost two decades ago now, would hit that phase early on when biofilms  and fungal growths began to appear, and I'd hear my friends telling me, "Yeah, your tank is going to turn into a big pile of shit. Told you that you can't put that stuff in there."

Because that's what they've been told. The prevailing mindset in the hobby was that the appearance of these organisms was an indication of an unsuitable aquarium environment.

Anyone who's studied basic ecology and biology understands that the complete opposite is true. The appearance of these valuable life forms is an indicator that your aquatic environment is ideal to foster a healthy, diverse community of aquatic organisms, including fishes!

Exactly like in Nature.

I remember telling myself that this is what I knew was going to happen. I knew how biofilms and fungal growths appear on "undefended" surfaces, and that they are essentially harmless life forms, exploiting a favorable environment. I knew that fungi appear as they help break down leaves and botanicals. I knew that these are perfectly natural occurrences, and that they typically are transitory and self-limiting to some extent.

Normal for this type of aquarium approach. I knew that they would go away, but I also knew that there would be a period of time when the tank might look like a big pool of slimy shit. Or, rather, it'd look like a pile of slimy shit to those who weren't familiar with these life forms, how they grow, and how the natural aquatic habitats we love so much actually function and appear!

To reassure myself, I would stare for hours at underwater photos taken in the Amazon region, showing decaying leaves, biofilms,and fungi all over the leaf litter. I'd read the studies by researchers like Henderson and Walker, detailing the dynamics of leaf litter zones and how productive and unique they were.

I'd pour over my water quality tests, confirming for myself that everything was okay. It always was. And of course I would watch my fishes for any signs of distress...

I never saw them.

I knew that there wouldn't be any issues, because I created my aquariums with a solid embrace of basic aquatic biology; an understanding that an aquarium is not some sort of underwater art installation, but rather, a living, breathing microcosm of organisms which work together to create a biome..and that the appearance of the aquarium only tells a small part of the story.


I knew that this type of aquatic habitat could be replicated in the aquarium successfully. I realized that it would take understanding, trial and error, and acceptance that the aquariums I created would look fundamentally different than anything I had experienced before.


I knew I might face criticism, scrutiny, and even downright condemnation from some quarters for daring to do something different, and then for labeling what most found totally distasteful, or have been conditioned by "the hobby" for generations to fear, as simply  "a routine part of the process."

It's what happens when you venture out into areas of the hobby which are a bit untested. Areas which embrace ideas, aesthetics, practices, and occurrences which have existed far out of the mainstream consciousness of the hobby for so long. Fears develop, naysayers emerge, and warnings are given.

Yet, all of this stuff- ALL of it- is completely normal, well understood and documented by science, and in reality, comprises the aquatic habitats which are so successful and beneficial for fishes in both Nature and the aquarium. We as a hobby have made scant little effort over the years to understand it. And once you commit yourself to studying, understanding, and embracing life on all levels, the world of natural, botanical-style aquariums and its untapped potential opens upon to you.

Mental shifts are required. Along with study, patience, time, and a willingness to look beyond hobby forums, aquarium literature, and aquascaping contests for information. A desire to roll up your sleeves, get in there, ignore the naysayers, and just DO.

Don't be afraid of things because they look different, or somehow contrary to what you've heard or been told by others is "not healthy" or somehow "dangerous." Now sure, you can't obey natural "laws" like the nitrogen cycle, understanding pH, etc. 

You can, however, question things you've been told to avoid based on superficial explanations based upon aesthetics.

Mental shifts.

Stuff that makes you want to understand how life forms such as fungi, for example, arise, multiply, snd contribute to the biome of your aquarium. 

Let's think about fungi for a minute...a "poster child" for the new way of embracing Nature as it is.

Fungi reproduce by releasing tiny spores that then germinate on new and hospitable surfaces (ie, pretty much anywhere they damn well please!). These aquatic fungi are involved in the decay of wood and leafy material. And of course, when you submerge terrestrial materials in water, growths of fungi tend to arise. Anyone who's ever "cured" a piece of wood for your aquarium can attest to this!

Fungi tend to colonize wood because it offers 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?

And of course, fishes and invertebrates which live amongst and feed directly upon the fungi and decomposing leaves and botanicals contribute to the breakdown of these materials as well! Aquatic fungi can break down the leaf matrix and make the energy available to feeding animals in these habitats. And look at this little gem I found in my research:

"There is evidence that detritivores selectively feed on conditioned leaves, i.e. those previously colonized by fungi (Suberkropp, 1992; Graca, 1993). Fungi can alter the food quality and palatability of leaf detritus, aecting shredder growth rates. Animals that feed on a diet rich in fungi have higher growth rates and fecundity than those fed on poorly colonized leaves. Some shredders prefer to feed on leaves that are colonized by fungi, whereas others consume fungal mycelium selectively..."

"Conditioned" leaves, in this context, are those which have been previously colonized by fungi! They make the energy within the leaves and botanicals more available to higher organisms like fishes and invertebrates! 

The aquatic fungi which will typically decompose leaf litter and wood are the group known as “aquatic hyphomycetes”. Another group of specialists, "aero-aquatic hyphomycetes," colonize submerged plant detritus in stagnant and slow- flowing waters, like shallow ponds, puddles, and flooded forest areas. Fungal communities differ between various environments, such as streams, shallow lakes and wetlands, deep lakes, and other habitats such as salt lakes and estuaries.

And we see them in our own tanks all the time, don't we? Sure, it's easy to get scared by this stuff...and surprisingly, it's even easier to exploit it as a food source for your animals! We just have to make that mental shift... As the expression goes, "when life gives you lemons, make lemonade!"


I knew when I started Tannin  that I had to "walk the walk." I had to explain by showing my tanks, my work, and giving fellow hobbyists the information, advice, and support they needed in order to confidently set out on their own foray into this interesting hobby path.

I'm no hero. Not trying to portray myself as a visionary.

The point of sharing my personal experience is to show you that trying new stuff in the hobby does carry risk, fear, and challenge, but that you can and will persevere if you believe. If you push through. IF you don't fear setbacks, issues, criticisms from naysayers.

You have to try. In my case, the the idea of throwing various botanical items into aquariums is not my invention. It's not a totally new thing. People have done what I've done before. Maybe not as obsessively or thoroughly presented (and maybe they haven't built a business around the idea!), but it's been done many, many times.

The fact is, we can and should all take these kinds of journeys.

Stay the course. Don't be afraid. Open your mind. Study what is happening. Draw parallels to the natural aquatic ecosystems of the world. Look at this "evolution" process with wonder, awe, and courage.

And know that the pile of decomposing leaves, fungal growth, and detritus that you're looking at now is just a steppingstone on the journey to an aquarium which embrace nature in every conceivable way.

Stay brave. Stay curious. Stay diligent. Stay observant...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

Transitional Habitats...A new aquarium hobby frontier?

We've spent a lot of time over the least several years talking about the idea of recreating specialized aquatic systems. We've talked a lot about transitional habitats- ecosystems which alternate between terrestrial and aquatic at various times of the year.  These are compelling ecosystems which push the very limits of conventional aquarium practice. 

As you know, we take a "function first" approach, in which the aesthetics become a "collateral benefit" of the function. Perhaps the best way to replicate these natural aquatic systems inner aquariums is to replicate the factors which facilitate their function. So, for example, let's look at our fave habitats, the flooded forests of Amazonia or the grasslands of The Pantanal.

To create a system that truly embraces this idea in both form and function, you'd start the system as a terrestrial habitat. In other words, rather than setting up an "aquarium" habitat right from the start, you'd be setting up what amounts to a terrarium. Soil/sand, terrestrial plants and grasses, leaves, seed pods, and "fallen trees/branches" on the "forest floor."


You'd run this system as a terrestrial display for some extended period of time- perhaps several weeks or even months, if you can handle it- and then you'd "flood" the terrestrial habitat, turning it into an aquatic one. Now, I'm not talking about one of our "Urban Igapo" nano-sized tanks here- I"m talking about a full-sized aquarium this time.  

This is different in both scale and dynamic. After the "inundation", it's likely that many of the plants and grasses will either go dormant or simply die, adding other nutrient load in the aquarium.

A microbiome of organisms which can live in the aquatic environment needs to arise to process the high level of nutrients in the aquarium. Some terrestrial organisms (perhaps you were keeping frogs?) need to be removed and re-housed.

The very process of creating and populating the system during this transitional phase from terrestrial to aquatic is a complex, fascinating, and not entirely well-understood one, at least in the aquarium hobby. In fact, it's essentially a virtually unknown one. We simply haven't created all that many systems which evolve from terrestrial to aquatic.

Sure, we've created terrariums, paludariums, etc. We've seen plenty of "seasonally flooded forest" aquairums in biotope aquarium contests...But this is different. Rather than capturing a "moment in time", recreating the aquatic environment after the inundation, we're talking about recreating the process of transformation from one habitat to another.

Literally, creating the aquatic environment from a terrestrial one.

Psychologically, it would be sort of  challenging!

I mean, in this instance, you've been essentially running a "garden" for several months, enjoying it and meeting the challenges which arise, only to embark several months later on a process which essentially destroys what you've created, forcing you to start anew with an entirely different environment, and contend with all of its associated challenges (the nitrogen cycle, nutrient control, etc.)

Modeling the process. 

Personally, I find this type of approach irresistible. Not only do you get to enjoy all sorts of different aspects of Nature- you get to learn some new stuff, acquire new skills, and make observations on processes that, although common in Nature, were previously unrecorded in the aquarium hobby. 


You'll draw on all of your aquarium-related skills to manage this transformation. You'll deal with a  completely different aesthetic- I mean, flooding an established, planted terrestrial habitat filled with soils and plants will create a turbid, no doubt chaotic-looking aquascape, at least initially. 


This is absolutely analogous to what we see in Nature, by the way.Seasonal transformations are hardly neat and tidy affairs. 

Yes, we place function over form. However, that doesn't mean that you can't make it pretty! One key to making this interesting from an aesthetic perspective is to create a hardscape of wood, rocks, seed pods, etc. during the terrestrial phase that will please you when it’s submerged.

You'll need to observe very carefully. You'll need to be tolerant of stuff like turbidity, biofilms, algae, decomposition- many of the "skills"we've developed as botanical-style aquarists.You need to accept that what you're seeing in front of you today will not be the way it will look in 4 months, or even 4 weeks.

You'll need incredible patience, along with flexibility and an "even keel.”

We have a lot of the "chops" we'll need for this approach already! They simply need to be applied and coupled with an eagerness to try something new, and to help pioneer and create the “methodology”, and with the understanding that things may not always go exactly like we expect they should.

For me, this would likely be a "one way trip", going from terrestrial to aquatic. Of course, much like we've done with our "Urban Igapo" approach, this could be a terrestrial==>aquatic==>terrestrial "round trip" if you want! That's the beauty of this. You could do a complete 365 day dynamic, matching the actual wet season/dry season cycles of the habitat you're modeling.


The beauty is that, even within our approach to "transformational biotope-inspired" functional ecosystems, you CAN take some "artistic liberties" and do YOU. I mean, at the end of the day, it's a hobby, not a PhD thesis project, right?

Yeah. Plenty of room for creativity, even when pushing the state of the art of the hobby! Plenty of ways to interpret what we see in these unique ecosystems.

Habitats which transition from terrestrial to aquatic require us to consider the entire relationship between land and water- something that we have paid scant little attention to in the aquarium hobby, IMHO. 

And this is unfortunate, because the relationships and interdependencies between aquatic habitats and their terrestrial surroundings are fundamental to our understanding of how they evolve and function.

There are so many other ecosystems which can be modeled with this approach! Floodplain lakes, streams, swamps, mud holes...I could go on and on and on. The inspiration for progressive aquariums is only limited to the many hundreds of thousands of examples which Nature Herself has created all over the planet.

We should look at nature for all of the little details it offers. We should question why things look the way they do, and postulate on what processes led to a habitat looking and functioning the way it does- and why/how fishes came to inhabit it and thrive within it.

With more and more attention being paid the overall environments from which our fishes come-not just the water, but the surrounding areas of the habitat, we as hobbyists will be able to call even more attention to the need to learn about and protect them when we create aquariums based on more specific habitats.

The old adage about "we protect what we love" is definitely true here!

And the transitional aquatic habitats are a terrific "entry point"into this exciting new area of aquarium hobby work.

Stay inspired. Stay creative. Stay observant. Stay resourceful. Stay diligent...

And Stay Wet.


Scott Fellman

Tannin Aquatics 

Someplace like...home?

Like so many of you, I am utterly awed by the sheer variety of tropical fish species that we've managed to breed in our aquariums over the decades. This is a testimony to the skill set and dedication of talented hobbyists and commercial breeders worldwide. And with obvious implications for some wild populations of fishes whose habitats arena danger, the idea of breeding fishes is a timely one.

Of course, there are absolutely benefits to a well-managed wild fishery, too, including protection of resources, economic benefits to indigenous peoples, and the preservation of wild populations. Programs like Project Piaba in Brazil have shown the tangible benefits to the people, environment, and the fishes that may be had with a properly-managed program of sourcing wild-caught fishes.

And, when it comes to the way we keep our fishes in the hobby on an everyday basis, I find a very interesting dichotomy here...

Have you ever thought about the way we've "domesticated" the fishes that we keep in our aquariums? I mean, the way we have sort of categorically "made" fishes more accommodating of the environmental conditions that we would like to provide them with in our aquariums? For example,  we've proudly advertised that fishes like Discus don't require soft, acidic water to thrive and reproduce. In fact, a number of breeders spawn and rear them in harder, more alkaline conditions.

This is interesting and makes me think about this from multiple angles...good and bad.

As you know, I tend to spend a fair amount of time snooping around the scientific literature online, looking for tidbits of information that might fit nicely into our fascination and evolving technique with natural blackwater and brackish- aquariums.

It's a pretty fun, albeit geeky- pastime, really- and quite educational, too!

And one of the interesting things about sifting through much of the scientific stuff is that you can occasionally find bits and pieces of information which may not only confirm a "hunch" that you have had about something- these data can sometimes send you into an entirely new direction! (I know that it can, lol!)

As a lover of brackish-water habitats, I've spent a lot time over the years researching suitable fishes and other aquatic organisms from this environment for aquarium keeping. I've made a lot of interesting discoveries about brackish water habitats and the fishes which supposedly occur in them. 

Notice I use the term "supposedly..?"

Interestingly, many of the fishes that we in the hobby have assigned the "brackish" moniker to are actually seldom found in these types of habitats. Perhaps some small populations of some of these fishes might be from mildly brackish environments, but many of them are primarily found in pure freshwater.

Perhaps through a combination of misinformation, assumption, and successful practice by a few hobbyists over the years, we've sort of attached the "brackish water fish" narrative to them in general.

Now, sure, many fishes can adapt to brackish water conditions, but I'm more fascinated by the fishes which are actually found naturally in these environments. And it's always interesting when you can find out that a fish which you have previously dismissed as not having typically come from this environment actually does come from it naturally!

It's like a little discovery!

One of those happy "surprises" is our good friend, the "Endler's Livebearer", Poceilia wingei. Many of you love this fish and keep it extensively. 

This popular fish is widely kept under "typical livebearer conditions" in the aquarium ( higher pH and harder water).

However, there are a number of wild populations form their native Venezuela which inhabit mildly brackish water coastal lagoons and estuaries, for example, Laguna de los Patos, near Cumana, which has definite ocean influence, although it is far less salty than researchers thought it may have been in the past. And the wild populations residing there might very well be considered "endangered", or at least, limited.

Now, this kind of stuff is not "revolutionary" from a hobby standpoint, as it seems like we've known this for some time. And although the fish are very adaptable, we don't hear all that much about keeping them in what we'd call "brackish" conditions (like typically SG of 1.003-1.005, although I like to push it a bit higher, lol). It's just interesting to ponder and kind of get your head around.

And with all of the popularity of this fish, it seems to me like the brackish water habitat for this species has not been embraced much from a hobby standpoint.

And I suppose it makes sense- it's far easier to simply give fishes harder, alkaline water than to "mess with adding salt" to their tanks for a lot of hobbyists. In addition, wild populations of these fishes are scant, as is natural habitat data, so indeed confirming with any great certainty that they are even still occurring in these types of habitats is sketchy.

And often, so-called 'populations" of fishes in these specialized habitats might have been distributed as a result of actions by man, and are not even naturally occurring there- further confounding things!

In general, the question about adding salt to livebearer tanks has been debated for a long time, and there are many views on the subject. Obviously, the ultimate way to determine if you should or should not add salt to an Endler's or other livebearer tank would be to consider the natural habitats of the population you're working with.


Easier said than done, because  the vast majority of them are now commercially or hobbyist bred for generations- especially Endler's- and wild collection data is not always easy to obtain.

I think the debate will go on for a long time!

Yet, with the increasing popularity of brackish water aquariums, we're hoping to see more experiments along this line for many different species! I was recently very happy to secure some specimens of the miserably-named "Swamp Guppy", Micropoceilia picta, a fish which absolutely does come from brackish water. And I have no intention of ever "adapting" them to environmental conditions which are more "convenient" for us hobbyists!

Now, you know I've always been a fan of sort of "re-adapting" or "re-patriating" even captive-bred specimens of all sorts of fishes (like "blackwater-origin" characins, cichlids, etc.) to more "natural" conditions (well, "natural" from perhaps a few dozen generations back, anyhow). I am of the opinion that even "domesticated" fishes can benefit from providing them with conditions more reminiscent of those from the natural habitats from which they originated.

Although I am not a geneticist or biological ethicist, I never will buy into the thought that a few dozen captive generations will "erase" millions of years of evolutionary adaptation to specific habitats, and that re-adapting them to these conditions is somehow "detrimental" to them. Something just seems "off" to me about that thinking.

I just can't get behind that.

Now, even more compelling "proof" of that it's not so "cut-and-dry" is that many of the recommended "best practices" of breeding many so-called "adaptable" species are to do things like drop water temperatures, adjust lighting, or perform water exchanges with peat-influenced water, etc....stuff intended to mimic the conditions found in the natural habitats of the fishes...

I mean...WTF? Right? 

Like, only give the fishes their "natural" conditions when we want to breed them? Really? That mindset just seems a bit odd to me...

Of course, there are some fishes for which we don't really make any arguments against providing them with natural-type environmental conditions, such as African rift lake Cichlids.

I find this absolutely fascinating, from a "hobby-philosopher" standpoint!

And then, there are those fishes which we have, for various reasons (to minimize or prevent the occurrence of diseases) arbitrarily decided to manipulate their environment deliberately away from the natural characteristics under which they evolved for specific reasons. For example, adding salt to the water for fishes that are typically not known to come from brackish habitats.

Examples are annual Killifishes, such as Nothobranchius, which in many cases don't come from brackish environments naturally, yet we dutifully add salt to their water as standard practice. The adaptation to a "teaspoon of salt per gallon" or so environment is done for prophylactic reasons, rather than what's "convenient" for us- a rather unique case, indeed...and again, something that I find fascinating to look at objectively.

Is salt simply the easiest way to prevent parasitic diseases in these fishes, or are there other ways which don't require such dramatic environmental manipulations?

And then, of course, there are those unexpected populations of fishes, like various Danios and Gold Tetras, for example, which are found in mildly brackish conditions...Compelling, interesting...yet we can't conclude that all Gold Tetras will benefit from salt in their water, can we?

And, as we evolved to a more sustainable hobby, with greater emphasis on captive -bred or carefully-sourced wild fishes, and as more wild habitats are damaged or lost, will we also lose valuable data about the wild habitats of the fishes we love so much?  

Data which will simply make the "default" for many fishes to be "tap water?"

I hope not.

Is it possible, though, that we've been so good at "domesticating" our fishes to our easier-to-provide tap water conditions- and our fishes so adaptable to them- that the desire to "repatriate" them to the conditions under which they've evolved is really more of a "niche" thing for geeky hobbyists, as opposed to a "necessary for success" thing?

I mean, how many Discus are now kept and bred exclusively in hard, alkaline water- markedly different than the soft, acid blackwater environmental conditions under which they've evolved for eons? Am I just being a dreamer here, postulating without hard data that somehow the fishes are "missing something" when we keep and breed them in conditions vastly different than what the wild populations come from?

Do the same genetics which dictate the color patterns and fin morphology also somehow "cancel out" the fish's "programming" which allows them to be healthiest in their original native conditions?

How do we reconcile this concept?

In the end, there are a lot of variables in the equation, but I think that the Endler's discussion is just one visible example of fishes which could perhaps benefit from experimenting with "throwback" conditions. I'm by no means anything close to an expert on these fish, and my opinions are just that- opinions. Commercially, it may not be practical to do this, but for the hobbyist with time, resources, and  inclination, it would be interesting to see where it takes you.  

Like, would the same strain kept in both brackish and pure freshwater habitats display different traits or health characteristics?

Would there even be any marked differences between specimens of certain fishes kept under "natural" versus "domesticated" conditions? Would they show up immediately, or would it become evident only after several generations? And again, I think about brackish-water fishes and the difficulty of tracing your specimens to their natural source, which makes this all that much more challenging!

I look forward to many more such experiments- bringing natural conditions to "domesticated" fishes, and perhaps unlocking some more secrets...or perhaps simply acknowledging what we all know:

That there truly is "no place like home!"

Stay observant. Stay curious. Stay adventurous. Stay resourceful. Stay experimental. Stay relentless...

And Stay Wet.


Scott Fellman

Tannin Aquatics