May 30, 2023

One of the great joys in creating and working with botanical method aquairums is that we have such a wide variety of natural habitats to take inspiration from. And, as we've discussed here over the years, it's not just types of natural aquatic habitats or specific locales- it's seasons and cycles that we can emulate in our tanks as well.

I find it fascinating to think about how we can emulate the environmental characteristics of aquatic habitats during certain times of the year, such as the "wet" and "dry" seasons...and the idea of actually "operating" your aquarium to spur the environmental changes which take place during these transitions.

Do we create true seasonal variations for our aquariums? I mean, changing up lighting duration, intensity, angles, colors, increasing/decreasing water levels or flow?

With all of the high tech LED lighting systems, electronically controlled pumps; even programmable heaters- we can vary environmental conditions to mimic what occurs in our fishes' natural habitats during seasonal changes as never before. I think it would be very interesting to see what kinds of results we could get with our fishes if we went further into environmental manipulations than we have been able to before.

I mean, sure, hobbyists have been dropping or increasing temps for spawning fishes forever, and you'll see hobbyists play with light durations. Ask any Corydoras breeder. However, these are typically only in the context of defined controlled breeding experiments.

Why not simply research and match the seasonal changes in their habitat and vary them accordingly "just because", and see if you achieve different results?

We've examined the interesting Igapo and Varzea habitats of The Amazon for years now, and how these seasonally-inundated forest floors ebb and flow with aquatic life during various seasons.

And, with the "Urban Igapo", we've "operated" tanks on "wet season/dry season" cycles for a few years now, enjoying very interesting results.

I think it would be pretty amazing to incorporate gradual seasonal changes in our botanical method aquariums, to slowly increase/decrease water levels, temperature, and lighting to mimic the rainy/dry seasonal cycles which affect this habitat.

What secrets could be unlocked?

How would you approach this?

You'd need some real-item or historical weather data from the area which you're attempting to replicate, but that's readily available from multiple sources online. Then, you could literally tell yourself during the planning phases of your next tank that, "This aquarium will be set up to replicate the environmental conditions of the Igarape Panemeo in May"- and just run with it.

What are some of the factors that you'd take into account when planning such a tank? Here are just a few to get you started:

-water temperature

-ph

-water depth

-flow rate

-lighting conditions

-percentage of coverage of aquatic plants (if applicable)

-substrate composition and depth

-leaf litter accumulation

-density of fish population

-diversity of fish population

-food types

...And the list can go on and on and on. The idea being to not just "capture a moment in time" in your aquarium, but to pick up and run with it from there!

Yes, we love the concept of seasonality in our botanical method world- but not just because they create interesting aesthetic effects- but because replicating seasonal changes brings out interesting behaviors and may yield health benefits for our fishes that we may have not previously considered.

The implications of seasonality in both the natural environment- and, I believe- in our aquariums- can be quite profound.

Amazonian seasonality, for example, is marked by river-level fluctuation, also known as "seasonal pulses." The average annual river-level fluctuations in the Amazon Basin can range from approximately 12'-45' /4–15m!!! Scientists know this, because River-water-level data has been collected in some parts of the Brazilian Amazon for more than a century! The larger Amazonian rivers fall into to what is known as a “flood pulse”, and are actually due to relatively predictable tidal surge.

And of course, when the water levels rise, the fish populations are affected in many ways. Rivers overflow into surrounding forests and plains, turning the formerly terrestrial landscape into an aquatic habitat once again.

Besides just knowing the physical environmental impacts on our fishes' habitats, what can we learn from these seasonal inundations?

Well, for one thing, we can observe their impact on the diets of our fishes.

In general, fish/invertebrates, detritus and insects form the most important food resources supporting the fish communities in both wet and dry seasons, but the proportions of invertebrates, fruits, and fish are reduced during the low water season. Individual fish species exhibit diet changes between high water and low water seasons in these areas...an interesting adaptation and possible application for hobbyists?

Well, think about the results from one study of gut-content analysis form some herbivorous Amazonian fishes in both the wet and dry seasons: The consumption of fruits in Mylossoma and Colossoma species (big ass fishes, I know) was significantly less during the low water periods, and their diet was changed, with these materials substituted by plant parts and invertebrates, which were more abundant.

Tropical fishes, in general, change their diets in different seasons in these habitats to take advantage of the resources available to them.

Fruit-eating, as we just discussed, is significantly reduced during the low water period when the fruit sources in the forests are not readily accessible to the fish. During these periods of time, fruit eating fishes ("frugivores") consume more seeds than fruits, and supplement their diets with foods like leaves, detritus, and plankton.

Interestingly, even the known "gazers", like Leporinus, were found to consume a greater proportion of materials like seeds during the low water season.

The availability of different food resources at different times of the year will necessitate adaptability in fishes in order to assure their survival. Mud and algal growth on plants, rocks, submerged trees, etc. is quite abundant in these waters at various times of the year. Mud and detritus are transported via the overflowing rivers into flooded areas, and contribute to the forest leaf litter and other botanical materials, becoming nutrient sources which contribute to the growth of this epiphytic algae.

During the lower water periods, this "organic layer" helps compensate for the shortage of other food sources. And of course, this layer comprises an ecological habitat for a variety of organisms at multiple "trophic levels."

And of course, there's the "allochthonous input"- materials imported into the habitat from outside of it...When the water is at a high period and the forests are inundated, many terrestrial insects fall into the water and are consumed by fishes. In general, insects- both terrestrial and aquatic, support a large community of fishes.

So, it goes without saying that the importance of insects and fruits- which are essentially derived from the flooded forests, are reduced during the dry season when fishes are confined to open water and feed on different materials, as we just discussed.

And in turn, fishes feed on many of these organisms. The guys on the lower end of the food chain- bacterial biofilms, algal mats, and fungal growths, have a disproportionately important role in the food webs in these habitats! In fact, fungi are the key to the food chain in many tropical stream ecosystems. The relatively abundant detritus produced by the leaf litter is a very important part of the tropical stream food web.

Interestingly, some research has suggested that the decomposition of leaf litter in igapo forests is facilitated by terrestrial insects during the "dry phase", and that the periodic flooding of this habitat actually slows down the decomposition of the leaf litter (relatively speaking) because of the periodic elimination of these insects during the inundation.

And, many of the organisms which survive the inundation feed off of the detritus and use the leaf substratum for shelter instead of directly feeding on it, further slowing down the decomposition process.

AsI just touched on, much of the important input of nutrients into these habitats consists of the leaf litter and of the fungi that decompose this litter, so the bulk of the fauna found there is concentrated in accumulations of submerged litter.

And the nutrients that are released into the water as a result of the decomposition of this leaf litter do not "go into solution" in the water, but are tied up throughout in the "food web" comprised of the aquatic organisms which reside in these habitats.

This concept is foundational to our interpretation of the botanical method aquarium.

So I wonder...

Is part of the key to successfully conditioning and breeding some of the fishes found in these habitats altering their diets to mimic the seasonal importance/scarcity of various food items? In other words, feeding more insects at one time of the year, and perhaps allowing fishes to graze on detritus and biocover at other times?

And, you probably already know the answer to this question:

Is the concept of creating a "food producing" aquarium, complete with detritus, natural mud, and an abundance of decomposing botanical materials, a key to creating a more true realistic feeding dynamic, as well as an "aesthetically functional" aquarium?

Well, hell yes!

On a practical level, our botanical method aquariums function much like the habitats which they purport to represent, famously recruit biofilm and fungal growths, which we have discussed ad nasueum here over the years. These are nutritious, natural food sources for most fishes and invertebrates.

And of course, there are the associated microorganisms which feed on the decomposing botanicals and leaves and their resulting detritus.

Having some decomposing leaves, botanicals, and detritus helps foster supplemental food sources. Period.

And you don't need special botanicals, leaves, curated packs of botanicals, additives, or gear from us or anyone to create the stuff! Nature will do it all for you using whatever botanical materials you add to your aquarium!

Apparently, the years of us beating this shit into your head here on "The Tint" and elsewhere are finally striking a chord. There are literally people posting pics of their botanical method aquariums on social media every week with hashtags like #detriusthursday or whatever, preaching the benefits of the stuff that we've reviled as a hobby for a century!

That absolutely cracked me up the first time I saw people posting that. Five years ago, people literally called me an idiot online for telling hobbyists to celebrate the stuff...Now, it's a freaking hashtag. It's some weird shit, I tell you...gratifying to see, but really weird!

Now, we've briefly talked about how decomposing leaf litter and the resulting detritus it produces supports population of "infusoria"- a collective term used to describe minute aquatic creatures such as ciliates, euglenoids, protozoa, unicellular algae and small invertebrates that exist in freshwater ecosystems.

And there is much to explore on this topic. It's no secret, or surprise- to most aquarists who've played with botanicals, that a tank with a healthy leaf litter component is a pretty good place for the rearing of fry of species associated with blackwater environments!

It's been observed by many aquarists, particularly those who breed loricariids, gouramis, bettas, and characins, that the fry have significantly higher survival rates when reared in systems with leaves and other botanical present. This is significant...I'm sure some success from this could be attributed to the population of infusoria, etc. present within the system as the leaves break down.

And the insights gained by seeing first hand how fishes have adapted to the seasonal changes, and have made them part of their life cycle are invaluable to our aquarium practice.

It's an oft-repeated challenge I toss out to you- the adventurers, innovators, and bold practitioners of the aquarium hobby: follow Nature's lead whenever possible, and see where it takes you. Leave no leaf unturned, no piece of wood unstudied...push out the boundaries and blur the lines between Nature and aquarium.

Follow the seasons.

And place the aesthetic component of our botanical method aquarium practice at a lower level of importance than the function.

I'm fairly certain that this idea will make me even less popular with some in the aquarium hobby crowd who feel that the descriptor of "natural" is their exclusive purview, and that aesthetics reign supreme..Hey, I love the look of well-crafted tanks as much as anyone...but let's face it, a truly "natural" aquarium needs to embrace stuff like detritus, mud, decomposing botanical materials, varying water tint and clarity, etc.

Yes, the aesthetics of botanical method tanks might not be everyone's cup of tea, but the possibilities for creating more self-sustaining, ecologically sound microcosms are numerous, and the potential benefits for fishes are many.

It goes back to some of the stuff we've talked about before over the years here, like "pre-stocking"aquariums with lower life forms before adding your fishes- or at least attempting to foster the growth of aquatic insects and crustaceans, encouraging the complete decomposition of leaves and botanical materials, allowing biocover ("aufwuchs") to accumulate on rocks, substrate, and wood within the aquarium, utilization of a refugium, etc.during the startup phases of your tank.

All of these things are worth investigating when we look at them from a "functionality" perspective, and make the "mental shift" to visualize why a real aquatic habitat looks like this, and how its elegance and natural beauty can be every bit as attractive as the super pristine, highly-controlled, artificially laid out "plant-centric" 'scapes that dominate the minds of most aquarists when they hear the words "natural" and "aquarium" together!

Particularly when the "function" provides benefits for our animals that we wouldn't appreciate , or even see- otherwise.

At Tannin, we've pushed rather unconventional hobby viewpoints since our founding in 2015. As an aquarist, I've had these viewpoints on the hobby for decades. A desire to accept the history of our hobby, to understand how "best practices" and techniques came into being, while being tempered by a strong desire to question and look at things a bit differently. To see if maybe there's a different- or perhaps-better-way to accomplish stuff.

Most of my time in the hobby has been occupied by looking at how Nature works, and seeing if there is a way to replicate some of Her processes in the aquarium, despite the aesthetics of the processes involved, or even the results.

As a result, I've learned to appreciate Nature as She is, and have long ago given up much of my "aquarium-trained" sensibilities to "edit" or polish out stuff I see in my aquariums, simply because it doesn't fit the prevailing aesthetic sensibilities of the aquarium hobby. Now, it doesn't mean that I don't care how things look...of course not!

Rather, it means that I've accepted a different aesthetic- one that, for better or worse in some people's minds- more accurately reflects what natural aquatic habitats really look like.

And the idea of replicating the seasonal changes in our aquariums is driven not primarily from aesthetics- but from function.

To sort of put a bit of a bow on this now rather unwieldy discussion about fostering and managing our own versions of seasonal ecological systems in our aquariums, let's just revisit once again how botanical materials accomplish this in our aquariums.

The idea that we are adding these materials not only to influence the aquatic environment in our aquariums, but to provide food and sustenance for a wide variety of organisms, not just our fishes. The fundamental essence of the botanical-method aquarium is that the use of these materials provide the foundation of an ecosystem.

The essence.

Just like they are in Nature.

And the primary process which drives this closed ecosystem is... decomposition.

Decomposition of leaves and botanicals not only imparts the substances contained within them (lignin, organic acids, and tannins, just to name a few) to the water- it serves to nourish bacteria, fungi, and other microorganisms and crustaceans, facilitating basic "food web" within the botanical-method aquarium- if we allow it to!

Decomposition of plant matter-leaves and botanicals- occurs in several stages.

It starts with leaching -soluble carbon compounds are liberated during this process. Another early process is physical breakup or fragmentation of the plant material into smaller pieces, which have greater surface area for colonization by microbes.

And of course, the ultimate "state" to which leaves and other botanical materials "evolve" to is our old friend...detritus.

And of course, that very word- as we've mentioned many times here, including just minutes ago- has frightened and motivated many hobbyists over the years into removing as much of the stuff as possible from their aquariums whenever and wherever it appears.

Siphoning detritus is a sort of "thing" that we are asked about near constantly. This makes perfect sense, of course, because our aquariums- by virtue of the materials they utilize- produce substantial amounts of this stuff.

Now, the idea of "detritus" takes on different meanings in our botanical-method aquariums...Our "aquarium definition" of "detritus" is typically agreed to be dead particulate matter, including fecal material, dead organisms, mucous, etc.

And bacteria and other microorganisms will colonize this stuff and decompose/remineralize it, essentially "completing" the cycle.

And, despite their impermanence, these materials function as diverse harbors of life, ranging from fungal and biofilm mats, to algae, to micro crustaceans and even epiphytic plants. Decomposing leaves, seed pods, and tree branches make up the substrate for a complex web of life which helps the fishes that we're so fascinated by flourish throughout the various seasons.

And, if you look at them objectively and carefully, these assemblages-and the processes which form them- are beautiful. We would be well-advised to let them do their work unmolested.

On a purely practical level, these processes accomplish the most in our aquariums if we let Nature do her work without excessive intervention.

An example? How about our approach towards preparing natural materials for use in our tanks:

After decades of playing with botanical method aquariums, I'm thinking that we should do less and less preparation of certain botanical materials-specifically, wood- to encourage a slower breakdown and colonization by beneficial bacteria and fungal growths.

The "rap" on wood has always been that it gives off a lot of tint-producing tannins, much to the collective freak-out of non-botanical-method aquarium fans. However, to us, all those extra tannins are not much of an issue, right? Weigh down the wood, and let it "cure" in situ before adding your fishes!

And then there is the whole concept of getting fishes into the tank as quickly as possible.

Like, why?

We should slow our roll.

I've written and spoken about this idea before, as no doubt many of you have: Adding botanical materials to your tank, and "pre-colonizing"with beneficial life forms BEFORE you ever think of adding fishes. A way to sort of get the system "broken in", with a functioning little "food web" and some natural nutrient export processes in place.

A chance for the life forms that would otherwise likely fall prey to the fishes to get a "foothold" and multiply, to help create a sustainable population of self-generating prey items for your fishes.

And that's a fundamental thing for us "recruiting" and nurturing the community of organisms which support our aquariums. The whole foundation of the botanical-method aquarium is the very materials- botanicals, soils, and wood- which comprise the "infrastructure" of our aquariums.The botanicals create a physical and chemical environment which supports these life forms, allowing them to flourish and support the life forms above them.

From there, we can "operate" our aquariums in any manner of ways.

Nature provides some really incredible inspiration for this stuff, doesn't it? Marshland and flooded plains and forests along rivers are like the "poster children" for seasonal change in the tropics.

Flood pulses in these habitats easily enable large-scale "transfers" of nutrients and food items between the terrestrial and aquatic environment. This is of huge importance to the ecosystem. As we've touched on before, aquatic food webs in the Amazon area (and in other tropical ecosystems) are very strongly influenced by the input of terrestrial materials, and this is really an important point for those of us interested in creating more natural aquatic displays and microcosms for the fishes we wish to keep.

Because the aquatic ecology is driven by the surrounding terrestrial habitats seasonally, the impact of leaves which fall into the aquatic habitats is very important.

What makes leaves fall off the trees in the first place? Well, it's simple- er, rather complex...but I suppose it's simple, too. Essentially, the tree "commands" leaves to fall off the tree, by creating specialized cells which appear where the leaf stem of the leaves meet the branches. Known as "abscission" cells. for word junkies, they actually have the same Latin root as the word "scissors", which, of course, implies that these cells are designed to make a cut!

And, in the tropical species of trees, the leaf drop is important to the surrounding environment. The nutrients are typically bound up in the leaves, so a regular release of leaves by the trees helps replenish the minerals and nutrients which are typically depleted from eons of leaching into the surrounding forests.

And the rapid nutrient depletion, by the way, is why it's not healthy to burn tropical forests- the release of nutrients as a result of fire is so rapid, that the habitat cannot process it, and in essence, the nutrients are lost forever.

Now, interestingly enough, most tropical forest trees are classified as "evergreens", and don't have a specific seasonal leaf drop like the "deciduous" trees than many of us are more familiar with do...Rather, they replace their leaves gradually throughout the year as the leaves age and subsequently fall off the trees.

The implication here?

There is a more-or-less continuous "supply" of leaves falling off into the jungles and waterways in these habitats throughout the year, which is why you'll see leaves at varying stages of decomposition in tropical streams. It's also why leaf litter banks may be almost "permanent" structures within some of these bodies of water!

Here's an easy "seasonal" experiment for you to try:

Manage and replicate this in the aquarium by adding leaves at different times of the year..increasing the quantities in some months and backing off during others. It's a relatively simple process with possible profound implications for aquariums.

And it makes me wonder...

What if we stopped replacing leaves and even lowered water levels or decreased water exchanges in our tanks to correspond to, for example, the Amazonian dry season (June to December)? What would it do?

If you consider that many fishes tend to spawn in the "dry" season, concentrating in the shallow waters, could this have implications for breeding or growth in fishes?

I think so.

Just a few easy ideas...each with a promise and a potential to change the way we manage botanical method aquariums, and impact the way we look at so-called "natural" aquariums in the first place!

And, with all of the research data from the wild habitats of our fishes available easier than ever before, the time is right to start these bold experiments!