We throw out s lot of rather unorthodox ideas here, don't we?
One of my fave ideas has to do with the idea of our botanical-style/blackwater aquariums being able to produce supplemental food for our fishes. 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 our fishes. 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!
If we look at ecology of natural blackwater ecosystems, they tend to be classified as "impoverished" by ecologists, in terms of ion and mineral compositions. However, that's not the whole story- at least, not as it pertains to food production in these habitats!
It shouldn't really come as a surprise that these aquatic systems offer significant food resources to the fishes which reside in them, because of the proximity to forests. Indeed, flooded forest floors, or streams which meander through forested areas offer enormous food production potential for fishes.
The main sources of sustenance for fishes are the food webs, constructed by the flooded forests, aquatic herbaceous vegetation, and algae. Allochthonous sources (remember that term?) such as detritus and botanical materials (eg. leaves) are the main pathways for energy and nutrients provided by the forests to the aquatic habitats.
Phytoplankton in these so-called "impoverished" blackwater environments is something that we've likely downplayed!
In the rainy season, the main flow of what ecologists call "biomass" into the food web comes from the surrounding forests. Also, studies have found that, in the backwaters of the main tributaries, the floating submerged leaves of marginal vegetation are colonized by dense aggregations of epiphytes.
"Floating submerged leaves..."
Just think about that for a few minutes...
Interestingly, both algae and macrophytes -aquatic plants which grow in and around the water (emerged, submerged, floating, etc.) enter into aquatic food webs mostly in form of detritus (fine and coarse particulate organic matter) or being transported by water flow and settling onto the substrate.
I am not at all joking when I tell you that I'd
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 directly upon them, 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!).
Perhaps most interesting to us blackwater/botanical-style 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.
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.
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 plant matter (mainly leaves) 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 style aquarium, this is a pretty common occurrence, and I believe an important benefit of this type of system.
I am of the opinion that a botanical-style 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! It's well known by ecologists that, in many habitats, like inundated forests, 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 one again that a blackwater/botanical-style aquarium could be an excellent sort of "nursery" for many fish species!
For like the thousandth time here, we're pointing out the mind-blowing fact that the types of ecosystems we're enamored by excel at producing food for the fishes which reside in them.
So, what do fishes eat?
Well, a little of everything, really.
As you can see the physical structure of aquatic habitats plays a huge role in determining what the composition of the fish population is.
There are a lot of aquatic habitats in Nature which are filled with tangles of terrestrial plant roots, emergent vegetation, fallen branches, etc., which virtually fill small bodies of water completely.
These types of habitats are unique; they attract a large quantities of smaller fishes to the protection of their vast matrix of structures. Submerged fallen tree branches or roots of marginal terrestrial plants provide a large surface area upon which algae, biofilm, and fungal growth occurs. This, in turn, attracts higher life forms, like crustaceans and aquatic insects.
And yeah- that brings our friends, the fishes- to the party.
These are incredible habitats for fishes.
Can't we replicate such aquatic features in the aquarium?
Of course we can!
This idea is a fantastic expression of "functional aesthetics." It's a package that is a bit different than the way we would normally present an aquarium. We hesitate to densely pack an aquarium like this, don't we?
Why do you think this is?
I think that we hesitate, because- quite frankly- having a large mass of tangled branches or roots and their associated leaves and detritus in the cozy confines of an aquarium tends to limit the number, size, and swimming area of fishes, right?
Sure, it does...
On the other hand, I think that there is something oddly compelling, intricate, and just beautiful about complex, spatially "full" hardscapes. And when you take into account that these are actually very realistic, entirelyfunctional representations of certain natural habitats, it becomes all the more interesting!
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.
Every botanical, every leaf, every piece of wood, every substrate material that we utilize in our aquariums is a potential component of food production. Sustenance from within.
Think about it.
Stay creative. Stay thoughtful. Stay innovative. Stay observant...
And Stay Wet.