Shane's World Right Arrow Catfishology Right Arrow Natural Catfish Aquarium, Part 1 • Understanding habitats • Article © Shane Linder, uploaded January 01, 2002

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. An aerial view of the Rio Meta, Colombia just a few miles upstream from where it meets the Orinoco.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.
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.


Looking east across the Rio Orinoco from Puerto Carreño, Colombia towards Venezuela. The Orinoco is a typical black water river. Many beautiful loricariids are exported from here.
Looking east across the Rio Orinoco from Puerto Carreño, Colombia towards Venezuela. The Orinoco is a typical black water river. Many beautiful loricariids are exported from here.

Black Water Main River Channel
The second habitat of interest is amongst the big mid-river boulders that are home to many of the more colorful loricariids. To create this biotope, stack a number of large rounded rocks (try to use darker-colored rocks) coming to its greatest height in the center of the aquarium. It should look like a mountain in the middle of the tank. Once the rocks are stacked, add a one-inch substrate of fine sand over the rocks. Stones always look more natural when the substrate is added after the stones and the stones are all of the same material. This tank should also have substantially greater current than the river bank tank above. Loricariids collected in this environment in the Rio Orinoco, Venezuela include L200, L128, Leproacanthicus triactus, and several Pseudacanthicus (like L240a). In the Rio Xingu, Brazil, this habitat would house Hypancistrus zebra and Scobinancistrus aureatus.

The Rio Espino in southern Guarico State, Venezuela is a typical white water river.
The Rio Espino in southern Guarico State, Venezuela is a typical white water river.

The White Water Habitat
White waters originate in younger mountain ranges that are still eroding large amounts of minerals and soil. This gives the water a color similar to that of coffee with cream due to the amount of suspended sediments. In the rainy season, white waters can look more like moving mud slides than rivers. Driftwood usually becomes part of the habitat when the river erodes its banks and causes trees to fall in. Since the water has a higher mineral buffering capacity, it tends to remain neutral and the driftwood does not rot as quickly. While it is not feasible to replicate the water's color (you would not be able to see your fish), we can replicate several of the habitats. Keep the pH near neutral and the water medium soft to medium hard. White water fishes are amongst the most adaptable to fluctuations in hardness and pH and white water habitats are easy for most aquarists to replicate since they can utilize straight tap water.

The Driftwood Snag
During the rainy season, white water rivers greatly erode their banks and bring many trees crashing down. The fast current carries along the floating trees until enough trees are caught up together and form a snag. These snags provide important habitats, especially for many loricariids and doradids. To replicate this environment, simply fill the tank with driftwood. Try not to stack the wood in an esthetic arrangement; it always looks more natural when it is sort of just dumped in the tank. After the wood has been added, pour in a thin substrate of sand or gravel over the wood. In the Rio Tinaco, Venezuela this would be the typical habitat of Panaque nigrolineatus, P. maccus, Hypostomus plecostomoides, Lasiancistrus sp. (L92), Hypostomus villarsi (L 153), and Hypoptopoma thoracatum. This tank should also have a strong current replicated the river's flow around and through the snag. It will also need strong filtration as wood-eating loricariids produce copious amounts of waste.

Collecting in a small feeder stream of the Rio Guapo in Miranda State, Venezuela. This creek is home to large numbers of diamond tetras, Corydoras venezuelanus and Ancistrus brevifilis.
Collecting in a small feeder stream of the Rio Guapo in Miranda State, Venezuela. This creek is home to large numbers of diamond tetras, Corydoras venezuelanus, and Ancistrus brevifilis.

The Leaf Litter
White water rivers typically contain small channels and oxbows with a lesser current and in these areas a foot or more of dead leaves can cover the substrate. This tank should have a thin substrate of sand covered by 2-3 inches of old oak leaves. A few pieces of driftwood can be added as well. Given the slack current and shallow waters in these environments, they are also noticeably warmer than the main river and the water temperature can easily rise to the mid-90s (although this temperature is not recommended for the home aquarium). Amongst the leaves hide banjo cats, small auchenipterids, Otocinclus, and Rineloricaria. Collecting in the leaf litter in Cano Domingo, Venezuela I have caught Corydoras habrosus, C. septentrionalis, and C. venezuelanus "black." This is an attractive and easy to maintain tank, especially for the aquarist with a smaller aquarium that wishes to keep a diverse population of catfishes.

The River Bank
This is the tank for an aquarist that wants to go all out with a museum-quality display. Flat stones are glued (with silicone) across the entire back of the tank to form a false riverbank. Coming out from the gaps in the stones are several pieces of driftwood slanting down into the substrate to look like the exposed roots of trees on the bank. The driftwood pieces can then have attached plants and additional plants (like Java moss) can be stuffed into the remaining gaps in the stones. Next, lay down a gravel or sand substrate. The depth of the substrate will depend on whether the aquarist wants additional plants in the substrate. Finally, place several vines (such as Philodendron) with their roots hanging in the water and their leaves cascading down the sides of the aquarium. To prepare the terrestrial plants, simply place a small cutting in water near sunlight. Once the plant establishes a good root system, move it to the aquarium. This tank is a fair reproduction of the typical habitat of many Hypostomus, Farlowella, Sturisoma, small Pimelodids, Corydoras venezuelanus, and many Rineloricaria. If the tank is large enough, and the substrate is made up of fine sand, it also makes a natural home for sand-dwelling loricariids such as Loricaria, Planiloricaria, Aphanotorulus, and Loricariichthys or a large school of Corydoras.

Clear Water Habitats
Clear water habitats typically exist in piedmont steams where the substrate is a combination of rounded stones and sand/gravel. Since they are more shaded, and high in elevation, the stay much cooler with average temperatures in the low to mid 70s F. The water is typically clear, though it may turn white during the rainy season, very soft, and has a slightly acidic to neutral pH. In this habitat, we typically encounter fast water loricariids such as Chaetostoma and Parancistrus and pimelodids from the genus Rhamdia.

The Rio Sumapaz, a tributary of the upper Rio Magdalena, Colombia.
The Rio Sumapaz, a tributary of the upper Rio Magdalena, Colombia.

The Piedmont Stream
This aquarium's current should be very strong and a "long" style aquarium works better than a "high" aquarium. Simply cover the entire substrate with flat (2-3 inch deep) rounded river stones and be sure to leave lots of gaps between the stones. Next cover these stones with a second layer and then add a thin substrate of sand. This allows the fish to excavate their own homes. The water flow should unidirectional and this is accomplished through the use of powerheads and PVC pipe (see diagram). The lighting should also be bright to encourage algae growth.

Substrate of rounded pebbles
Substrate of rounded pebbles

Materials
All of the materials that you need to set up any biotope can be collected right out your back-door for free. Sand and driftwood can be collected from ocean beaches. Local streams and rivers are good sources for stones, driftwood, gravel, and sand. Another good source for items like stones, vines, and bamboo is your local garden center. If you live in a temperate area, you probably have all the leaves you could ever use laying around in your backyard (boil the leaves first to remove the tannins and so that they sink). In all of my years of using natural materials, I have never had a problem. Just make sure that all the items you collect in your forays are well washed first and then allowed to dry for a week. Always collect more stones, sand, and driftwood than you believe you will need so that you will have more options when aquascaping.

You will also need a saw, wood screws (plastic if you can find them), silicone, and suction cups. Use the saw to cut driftwood pieces to fit the tank exactly as you need them to. Wood screws are great for attaching several pieces of driftwood together to form a false driftwood snag or series of branching roots. Silicone is the best way to attach stones to the back of a tank. Suction cups can be attached to driftwood pieces either to make the wood stay in place or to keep it from floating or they can be attached to branching twigs that "hang down" into the tank.. Your aquascaping options are limited only by your imagination.

A small creek flowing into the Orinoco at Puerto Carreño. Looking down into the creek, I watched schools of Corydoras dart up and down its length.
A small creek flowing into the Orinoco at Puerto Carreño. Looking down into the creek, I watched schools of Corydoras dart up and down its length.

Conclusion
Walk away from this article down and go take a look at your tank(s). Does it have a layer of natural gravel, a piece of store bought driftwood, two rainbow rocks (or maybe you opted for lava rocks), and a plastic Amazon sword? If so, you have the generic aquarium that replicates no known habitat. Wouldn't your Panaque be happier in a driftwood snag, your Corydoras scrounging among the leaf litter, and your Raphael hiding amongst a faux riverbank? Why not break that tank down and build your catfishes a natural catfish aquarium? Here are some examples to get you started:

10 gal. driftwood
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.

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

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

L106
4) The same 40 gallon tank. This L 106 is right at home.

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

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