I don't want to steal your thread, but I have a quick question for Byron regarding the picture. If that is an authentic aquascape, then where do all the plants come from? I have looked at your tanks, and they all seem to be heavily planted. Is that not natural for the fish?
It is "natural for the fish" but it is not always authentic for most watercourses.
I'll explain below.
Yes, I have posted this some time back. This is a Venezuelan stream, worth keeping in mind, in connection with what I'll say below.
I'm sure Byron will come back here soon enough but I'll throw in what ( I think) I know. There are very few plants that grow with leaves under water. Most grow immersed with only the stems under water and the leaves grow out of the water. Planted tanks aren't exactly natural. However with so many leaves falling from the trees above that get swirled around into the water in nature, it works. Throwing handfuls of leaves into our tanks would just create a mess and create ammonia. Roots and broken branches are also normal hence the driftwood as a replacement. Hope that makes sense.
This is very true, and is one part of the picture.
Amazonia is a big place. In area, the Amazon basin is roughly the size of the continental USA minus Texas. It is not uniform. There is also the seasonal fact of flooded forest for half the year. Few rivers and streams contain aquatic vegetation, as the photos I posted illustrate. The Rio Guapore and Rio Negro are major exceptions. But in most cases, plants are still integral to the fish.
Rivers and streams that are within the forest are heavily shaded by the forest canopy and/or terrestrial marginal vegetation. This marginal vegetation frequently extends down into the water as branches and vines. The streambed is littered with fallen trees, branches and debris. This video link is a perfect example of the latter; note particularly the angelfish habitat. YouTube - Broadcast Yourself
This is also another cardinal tetra habitat. [The Paracheirodon axelrodi in this video are the Brazilian form, different from the Columbian/Venezuelan form that are in the video FranklinS linked. Can you see the difference?] Whichever, the species needs dim light and lots of cover. To replicate such a habitat in an aquarium would result in a very dark tank. But we can approach this in several ways. One is an aquascape like those in the previously posted photos. Another is to thickly plant the tank, which allows a bit more light for our benefit to observe our fish but the plants and particularly the floating plants shade the direct light for the benefit of the fish. The issue for the fish is twofold: minimal light, and plenty of secure cover in the water. Live plants achieve this, plus they improve water quality within the confines of the aquarium.
An equally important point though is that in most of these habitats--at least those in which our "forest fish" (tetra, pencilfish, hatchetfish, corys, angels, discus, etc) live--the rivers and streams flood their banks for half the year. The surrounding forest for hundreds of miles is under up to 30+ feet of water. These fish move into the flooded forest to spawn. The fry are hatched and raised among thick vegetation which is now submersed. My planted aquaria do replicate this half of the year, so in that sense it is especially natural to the fish.