The “community tank”: facts and myths.

What is a community tank?

In the broadest sense a community tank is an aquarium (freshwater or marine) in which the plants and animals therein are all compatible. This means the fishes won’t normally fight with other nor eat their tank mates (including the plants and other animals); the plants are compatible with each other and will survive with the fishes and other animals for a long period of time, and reproduce.

How are community tank inhabitants chosen?

Probably the best way to choose fishes (and other animals as well as plants) for a planned community tank is to first decide on the type of aquatic environment that is to be housed in the aquarium. This can be easily based on a given geographic area. For instance, one can choose to set up an aquarium of tropical rain forest species from South America, Central America or South East Asia. For a marine aquarium the coral reefs of the Caribbean or some area of the Indo-Pacific or Red Sea can be chosen. Remember, “reef tanks” can be either marine or freshwater and the word “reef” does not necessarily refer to a “coral reef”. A very satisfying marine reef-type tank can be set up using macro algae, invertebrates and fishes that are commonly found in Mississippi Sound rock reefs; no corals are found in such environments. Similarly, Hawaii has few coral species (owing to the cooler waters that surround the Hawaiian Island chain), and a typical Hawaiian reef will consist of volcanic rocks, sea urchins, snails, some shrimp, and a few colorful fishes.

A freshwater reef can be set up by using fishes found in the inshore rock habitats of either Lake Malawi or Lake Tanganyika. These fishes are quite colorful and live in dense communities similar to those found in marine coral reef environments. Additionally, there are even crabs and sponges that live in Lake Tanganyika and anyone lucky enough to obtain these animals could truly set up a unique freshwater reef community tank.

While we generally recommend that community tanks contain only plants and animals from a given geographic area, this obviously is not the only way to proceed. The basic thing to avoid is animals which will be unusually aggressive with each other, or those which will naturally prey on their tank mates. Keep in mind that very few predator fishes are highly aggressive (even though predation is probably the highest form of aggression!). Generally, the most aggressive fishes are those that are herbivores. Such herbivorous fishes must be aggressive to protect patches of algae growth. This is why most marine damselfishes are highly aggressive while groupers (which eat live fishes) are not.

Are some fishes just not good community fishes?

It is often thought that cichlids are poor community fishes. In fact, with few exceptions most cichlids can do well in a community tank set up. The trick is to choose cichlids that will thrive in the size tank chosen to house the community. Cichlids, range in size from about 1 inch to over 3 feet long. Even the biggest cichlids can be housed in a community tank if the aquarium is large enough to accommodate them at their largest size.
Piranhas are probably the most difficult fishes to set up in a community tank. However, once the habits and ecology of these fishes are understood it should be simple enough to set up a community tank with piranhas. For example, common suckermouth catfishes (Hypostomus plecostomus), the larger silver dollar fishes and pacus, oscars (Astronotus ocellatus), tiger characins (Hoplias malabaricus), peacock bass (Cichla ocellarus), and others can be considered for such a community tank. This community tank should be large (at least 300 gallons) and the fishes should all be acquired as juveniles so that they grow up together.

What are some other examples of good community tank fishes?

A good, small (less than 30 gallons) South American community tank would consist of (1) 12-18 cardinal (or neon) tetras, (2) 6-8 Corydoras palleatus, (3) 4-6 Otocinclus species, (4) 8-12 lemon tetras, (5) 1 pair of common (blue or gold) rams and/or (6) 1 pair of an Apistogramma species, (7) one or two small suckermouth catfishes such as Otocinclus arnoldi, and (8) 4-6 silver or marble hatchetfishes. This tank could be planted with a specimen of Amazon swordplant, a number of pygmy chain swordplants, several corkscrew val plants and other background and foreground plants. African root wood pieces would make decorations and add to the available hiding places and provide potential spawning sites for the small cichlids.

An example of a Lake Malawi tank of 50 gallons or larger would include a trio (1 male & two females) each of: (1) golden Malawi cichlid (Melanochromis auratus), (2) zebra cichlid (any color variety), (3) purple & gold mbuna (Pseudotropheus acei); (4) a pair of sunshine peacocks (Aulonocara sp.), and (5) a Synodontis njassae catfish. More species can be added if the size of the tank is increased; don’t mix different species of peacock cichlids (due to the fact that they tend to hybridize in captivity). Expect the cichlids to reproduce and thereby increase the tank population. Use several pounds Texas holey rock and pieces of African root wood to provide plenty of hiding places for female and juvenile fishes.

If there are any questions please call us at 816/842-5936.

(1) Plan your tank acquisitions and stick to it, then stop!

(2) Don’t be, or allow customers to be, an impulse buyer of fishes; always read a good reference book on each species. Choose species that are likely to occur together in nature.

(3) Use gravel, rocks, driftwood, plants, decorations and tank size suitable for the temperament and needs of each species as well as the community.

(4) Use appropriate lighting; some species and community groups may need low light conditions.

(5) Condition the water, as needed, but pay attention to maintaining good water quality (through regular water changes and proper filtration) rather than specific parameters.