Introduction
I have always been of the opinion that captive fishes look, and do, their best when kept in an aquarium that attempts to replicate their natural habitat. I also believe that the best way to replicate a natural habitat is to use natural materials. An aquarium substrate of sand or gravel that the aquarist has collected from a creek will always look better than store bought gravel. Commercial substrates, for example, are sold by color and size, which creates a rather bland substrate that consists of all the same color of similar sized gravel. Mother Nature, however, does not exercise this type of quality control. The other pitfall that many aquarists make is that all of their aquariums end up looking the same because they replicate the same generic habitat in all their tanks. Instead of three tanks with a mixture of gravel, rocks, plants, and driftwood, why not have a tropical piedmont stream, a black water biotope, and a leaf litter tank? To get you started, I'll give the basic information for a number of catfish habitats and then talk about how to obtain your own materials.

In this section I will focus mainly on South American biotopes because catfishes from South America represent the great majority of species imported for the hobby and because I have the most experience in this region. The first thing that the hobbyist has to take into consideration is that there are basically three types of water. Waterways in the tropics are normally classified as black water, white water, or clear water. Black waters typically originate in older mountain ranges that, over the millennia, have been stripped of much of their mineral content. This creates a river system, such as the famous Rio Negro, that is considered very poor in nutrients. The lack of mineral buffers also means that black waters tend to have an acidic pH. When this acidic water comes into contact with vegetation, it often kills the plants that it comes into contact with. Along most black water rivers, it is very easy to see where the water's high point was in the wet season as all of the vegetation along the banks will have been killed or have had its leaves "burnt" off where they came into contact with the water. The dead vegetation then rots in the acidic water and this massive release of tannins stains the water. Not all black waters are equal and the water can range from the color of weak tea to black coffee. What all black waters do have in common is an acidic pH, usually between 3.5 and 6, and almost no measurable hardness.

Black waters are also known for their very colorful fishes. My theory is that the lack of visibility in these waters produces more colorful fishes for two reasons. First, because the fishes need to be more colorful in order to find each other, and second, they can adapt brighter colors because it is more difficult for predators to see them in this habitat. Camouflage simply becomes less important when a fish can become invisible by diving a few inches under the water's surface.

The Black Water Habitat
There are basically two black water habitats of interest to the aquarist. One is amongst the dead vegetation along the river banks, and the second is amongst the large boulders in the middle of the river channel. Both biotopes are very simple to create and maintain. The main drawback of these systems is the need for soft, almost pure, water. Finish off both black water tanks with a good dose of commercial, or homemade, black water extract. To make black water extract, simply boil a large pot of aquarium-safe peat and bottle the water once it is stained dark enough. One big chunk of peat will make several bottles of black water extract. The drawback is that making the extract really stinks up the kitchen.


A close up of the bank of the Orinoco. Note the reddish-colored sand.

The Black Water River Bank

For a river bank, lay down a thick substrate of white, or very light colored, sand which slopes up towards the back of the tank. Sticking up out of the sand should be a "forest" of driftwood pieces, use taller "driftwood trees", which reach the tank's surface in the back, and shorter ones in the front. This replicates the remains of small trees and bushes that have been killed by the acidic water. Finally, collect several small branching twigs and attach them to the back of the tank (as described below) to replicate overhanging branches that have had their leaves "burned" off. For those of you interested in cichlids, this is also the habitat of Altum angels and Uaru in the upper Rio Orinoco. Examples of catfish communities from this environment:

• Rio Cuyuni, Venezuela: Corydoras bondi, Platydoras costatus, Ancistrus, Cteniloricaria, Hypoptopoma guianense, Parotocinclus britski, Rineloricaria, Microglanis, Pimelodus blochi, P. albofasciatus, P. ornatus.
• Rio Atatpabo, Venezuela: Tatia, Corydoras osteocarus, Acanthodoras cataphractus, Orinocodoras eigenmanni, Pseudodoras niger, Liosomadoras oncinus, Acestridium.
• Rio Caura Venezuela: Sorubim lima, Pimelodus albofasciatus, Ancistrus, Lasiancistrus, Hemiancistrus, Tatia, Corydoras blochii, C. boehlkei, C. melanistius, C. osteocarus.

1) You do not need a big tank to have a natural tank. This 10 gallon driftwood snag is set up for, and replicates the natural habitat of, Panaque sp. LDA 68.

2) A 10 gallon "wet season" set up for Corydoras melini.

3) A 40 gallon tank which replicates a portion of riverbank in the Orinoco River.

4) The same 40 gallon tank. This L 106 is right at home.

5) A possible piedmont stream set up. This would be perfect for spawning Chaetostoma spp.

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