A Steady Diet of...

Hmm...ponder the possibilities here...

One of the most important functions of many botanically-influenced wild habitats is the creation and support of food webs. As we've discussed before in this blog, the leaf litter zones in tropical waters are home to a remarkable diversity of life, ranging from microbial to fungal, as well as crustaceans and insects...oh, and fishes, too!  These life forms are the basis of complex and dynamic food webs, which are one key to the productivity of these habitats.

By researching, developing, and managing our own botanically-influenced aquaria, particularly those with leaf litter beds, we may be on the cusp of finding new ways to create "nurseries" for the rearing of many fishes!

At least upon superficial examination, our aquarium leaf litter/botanical beds seem to function much like their wild counterparts, creating an extremely rich "microhabitat" within our aquariums. And reports form those of you who breed and rear fishes in your intentionally "botanically-stocked" aquariums are that you're seeing great color, more regularity in spawns, and higher survival rates from some species.

We're just beginning here, but the future is wild open for huge hobby-level contributions that can lead to some serious breakthroughs! 

For this reason, specialized grazing fishes are rather uncommon in streams that contain shifting sand substrates, especially where there is dense shading by overhanging trees and shrubs. However, in streams possessing silty or muddy bottoms, there is typically not enough aquatic plant or woody materials present to support an extensive community of periphyton sufficient to support grazing fishes.

In these types of habitats, many grazing fishes feed on our old fave, detritus- and other sediments that are rich in organic matter, especially during various times of the year when the periphyton is more limited. Stuff like fungi and diatoms provide additional nutrition for fishes that graze, so our decomposing leaf litter and seed pods and such are useful for supporting this growth! One only need scientific literature about the gut content analysis of various fishes to see that these items form the basic diet of a large number of fishes.

Major rivers like the Rio Negro are often called "impoverished" by scientists, in terms of plankton production. They also show little seasonal fluctuations in algal and bacterial populations. Other blackwater systems do show seasonal fluctuations, such as lakes and watercourses enriched with overflow in spring months.

At low water levels, the nutrients and population of these life forms are generally more dense. Creatures like hydracarines (mites), insects, like chironomids (hello, blood worms!), and copepods, like Daphnia, are the dominant fauna that fishes tend to feed on in these waters.  This is interesting to contemplate when we consider what to feed our fishes in aquariums, isn't it? Hmm...Why don't more commercial fish foods contain mostly aquatic insects? Hint, hint, hint, hint...

Anyways, these life forms, both planktonic and insect, tend to feed off of the leaf litter itself, as well as fungi and bacteria present in them as they decompose. The leaf litter bed is a surprisingly dynamic, and one might even say "rich" little benthic biotope, contained within the otherwise "impoverished" waters. And, as we've discussed before, it should come as no surprise that a large and surprisingly diverse assemblage of fishes make their homes within and closely adjacent to, these litter beds. These are little "food oasis" in areas otherwise relatively devoid of food. The fishes are not there just to look at the pretty leaves.

 

It's not really that much different in the aquarium, is it? I mean, as the leaves and botanicals break down, they are acted upon by fungi and bacteria, the degree of which is dependent upon the available food sources. Granted, with fishes in a closer proximity and higher density than in many wild habitats, the natural food sources are usually not sufficient to be the primary source of food for our fishes- but they are one hell of a supplement, right? That's why, in a botanical-rich, leaf litter dominated aquarium, you see the fishes spending a lot of time foraging in and among the litter...just like in Nature.

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

Bacterial biofilms, as we've discussed many times before, contain a complex mix of sugars, bacteria, and other materials, all of which are relatively nutritious for animals which feed on them. It therefore would make a lot of sense that a botanical-influenced aquarium with a respectable growth of biofilm would be a great place to rear fry! Maybe not the most attractive place, from an aesthetic standpoint- but a system where the little guys are essentially "knee deep" in supplemental natural food at any given time is a beautiful thing to the busy fish breeder!

And what of the leaves themselves? Do our aquatic animals feed on them? Well, yes- and no. Some fishes, for example, Loricariids, will feed on some of the materials directly, rasping off surface tissues. Others, like certain characins (notably, Headstanders, Metynis, and similar fishes), will feed off of the algae growth, or aufwuchs, as it's collectively referred to, present on the botanicals and leaves.

Is it possible to create a real "active substrate", filled with these creatures, and to be able to "pre-stock' it with tons of small life forms prior to the introduction of fish? Would there be some way to replenish the population of these creatures (and thus the substrate itself) periodically? Yeah, I KNOW that it is. 

"Maybe we will finally overcome generations of fear over detritus and fungi and biofilms- the life-forms which power the aquatic ecosystems we strive to replicate in our aquariums. Maybe, rather than attempting to "erase" these things which go against our "Instagram-influenced aesthetics" of how we think that Nature SHOULD look, we might want to meet Nature where she is and work with her."

And then, we might see the real beauty- and benefits- of unedited Nature.

One of the important food resources in natural aquatic systems are what are known as macrophytes- aquatic plants which grow in and around the water, emerged, submerged, floating, etc. Not only do macrophytes contribute to the physical structure and spatial organization of the water bodies they inhabit, they are primary contributors to the overall biological stability of the habitat, conditioning the physical parameters of the water. Of course, anyone who keeps a planted aquarium could attest to that, right? 

One of the interesting things about macrophytes is that, although there are a lot of fishes which feed directlyupon them, in this context, the plants themselves are perhaps most valuable as a microhabitat for algae, zooplankton, and other organisms which fishes feed on. Small aquatic crustaceans seek out the shelter of plants for both the food resources they provide (i.e.; zooplankton, diatoms) and for protection from predators (yeah, the fishes!).

I have personally set up a couple of systems recently to play with this idea- botanical-influenced planted aquariums, and have experimented with going extended periods of time without feeding my fishes who lived in these tanks- and they have remained as fat and happy as when they were added to the tanks...

Something is there- literally!  

Perhaps most interesting to us blackwater/botanical-method aquarium people are epiphytes. These are organisms which grow on the surface of plants or other substrates and derive their nutrients from the surrounding environment. They are important in the nutrient cycling and uptake in both nature and the aquarium, adding to the biodiversity, and serving as an important food source for many species of fishes.

In the case of our aquatic habitats, like streams, ponds, and inundated forests, epiphytes are abundant, and many fishes will spend large amounts of time foraging the biocover on tree trunks, branches, leaves, and other botanical materials. Although most animals use leaves and tree branches for shelter and not directly as a food item, grazing on this epiphytic growth is very important.

Some organisms, such as nematodes and chironomids ("Bloodworms!") will dig into the leaf structures and feed on the tissues themselves, as well as the fungi and bacteria found in and among them. These organisms, in turn, become part of the diet for many fishes.

And the resulting detritus produced by the "processed" and decomposing pant matter is considered by many aquatic ecologists to be an extremely significant food source for many fishes, especially in areas such as Amazonia and Southeast Asia, where the detritus is considered an essential factor in the food webs of these habitats.

And of course, if you observe the behavior of many of your fishes in the aquarium, such as characins, cyprinids, Loricarids, and others, you'll see that in between feedings, they'll spend an awful lot of time picking at "stuff" on the bottom of the tank. In a botanical method aquarium, this is a pretty common occurrence, and I believe an important benefit of this type of system. 

I've said it many times, and it bears saying again:

I am of the opinion that a botanical-method  aquarium, complete with its decomposing leaves and seed pods, can serve as a sort of "buffet" for many fishes- even those who's primary food sources are known to be things like insects and worms and such. Detritus and the organisms within it can provide an excellent supplemental food source for our fishes!

Just like in Nature. 

Another interesting fact:

It's well known that in many habitats, like inundated forest floors, etc., fishes will adjust their feeding strategies to utilize the available food sources at different times of the year, such as the "dry season", etc. And it's also known that many fish fry feed actively on bacteria and fungi in these habitats...so I suggest once again that a blackwater/botanical-method aquarium could be an excellent sort of "nursery" for many fish species! 

You'll often hear the term "periphyton" mentioned in a similar context, and I think that, for our purposes, we can essentially consider it in the same manner as we do "epiphytic matter." Periphyton is essentially a "catch all" term for a mixture of cyanobacteria, algae, various microbes, and of course- detritus, which is found attached or in extremely close proximity to various submerged surfaces. Again, fishes will graze on this stuff constantly.

And then, of course, there's the allochthonous input that we talk about so much here.Foods from the surrounding environment, such as flowers, fruits, terrestrial insects, etc. These are extremely important foods for many fish species that live in these habitats. We mimic this process when we feed our fishes prepared foods, as stuff literally "rains from the sky!" Now, I think that what we feed to our fishes directly in this fashion is equally as important as how it's fed.

I'd like to see much more experimentation with foods like live ants, fruit flies, and other winged insects. Of course, I can hear the protests already: "Not in MY house, Fellman!" I get it. I mean, who wants a plague of winged insects getting loose in their suburban home because of some aquarium feeding experiment gone awry, right?

I think we need to let ourselves embrace this stuff and celebrate it for what it is: Life. Sustenance. Diversity. Foraging. I think that those of us who maintain blackwater. botanical- aqumethod ariums have made the "mental shift" to understand, accept, and even appreciate the appearance of this stuff.

We look at Nature.

Natural habitats are absolutely filled with this stuff...in every nook and cranny. It's like the whole game here- an explosion of life-giving materials, free for the taking...

A true gift from Nature. 

Yet, for a century or so in the hobby, our first instinct is to reach for the algae scraper or siphon hose, and lament our misfortune with our friends.

It need not be this way. Its appearance in our tanks is a blessing. 

Really.

You call it "mess." I call it "food."

Another "mental shift", I suppose...one which many of you have already made, no doubt. Or, I hope you have..or can.

I certainly look forward to seeing many examples of us utilizing "what we've got" to the advantage of our fishes! AGAIN:

A truly "natural" aquarium is not sterile. It encourages the accumulation of organic materials and other nutrients- not in excess, of course. Biofilms, fungi, algae...detritus...all have their place in the aquarium. Not as an excuse for lousy or lazy husbandry- no- but as supplemental food sources to power the life in our tanks.

Real gifts from Nature...that you can benefit from simply by "working the web" of life which arises without our intervention as soon as leaves, wood, and water mix.

Keep making those mental shifts. Meet Nature where it is. She won't let you down. I promise.

And then, there are those insects. You know, terrestrial ones, like ants, flies, spiders, etc. They're especially important to fishes which reside in streams in rain forests and other locales where the land and water interact extensively, like areas of riparium vegetation. Now, not everyone's cup of tea, I know, but could, for example, ants- which make up a surprisingly large part of the diet (based on gut content analysis) of some fishes like characins and even some cichlids in Amazon streams- be a practical supplement food for our fishes?

I can just see a sudden surge in the popularity of "Ant Farms" as hobbyists race to culture their own populations of these insects! 

In the forests of South America, Asia, and Africa, where streams run throughout the year, there are numerous "allochthonous resources" to be had, such as fruits, flowers, the aforementioned terrestrial insects, and seeds, which fall into the water and help comprise part of the diet of many fishes. Interestingly, it's thought that many of the fruit and seed-eating fishes (like Myleus, Metynnis, and other characins) don't actually destroy the seeds of fallen fruits when consuming them, and thus might actually be significant seed dispersal agent sfor riparian and floodplain trees in these areas!

And, interestingly,  lots of these fishes also consume insects and aquatic invertebrates, depending upon the season- a strategy which makes sense, as it takes advantage of "what's available" at different times of the year.

Now, there are a fair number of fishes that consume aquatic plants, or more properly- parts of aquatic plants- as part of their diet, such as Doradid catfishes and Anomostids. Often, they're also consuming epiphytic algae and such in the process. Now, I'm not suggesting to utilize plants in your aquascape for feeding purposes; however, it's not entirely out the the realm of reality to do this, right?

A lot of omnivorous fishes in the wild are removing the periphyton from the roots of floating plants in some streams, so it may make some sense to utilize these plants as sort of "for culture stations" in your aquascape to support the feeding habits of many fishes, such as characins, Danios, Barbs, etc.

It's interesting to contemplate designing a biotope or other aquarium around feeding, an important but often overlooked aspect of fish behavior (when it comes to tank design, that is!) With a little research, planning, and a lot of experimentation, what interesting discoveries can be made? What breakthroughs await? Combining our much evolved expertise in fish feeding with our love of aquascaping seems almost a natural combination, doesn't it?