Community tanks are aquaria that are designed to contain more than one species of fish. Most commonly they include a variety species that do not normally occur together in nature, for example angelfish from Brazil, swordtails from Mexico, and gouramis from South East Asia. The aim of such communities is to bring together fish that are compatible in temperament and water requirements, while using their different colours and behaviours to add interest and entertainment value.

Though not usually called community tanks, most marine aquaria fit into this category too, using fish from places as diverse as the Caribbean, Red Sea, and western Pacific Ocean.

Other aquarists prefer communities that represent particular locations, and combine fishes from a certain place with appropriate decorative materials including the right kinds of rocks and plants. The most popular of these geographically correct community tanks are those based around cichlids from the East African Rift Valley lakes of Lake Tanganyika and Lake Malawi.

Good community fish

For freshwater community tanks, there are large numbers of species that work well. Most of the livebearers, barbs, tetras, rasboras, danios, and rainbowfish are peaceful, though a few species are fin nippers, most notably tiger barbs and serpae tetras. Angelfish, gouramis, and dwarf catfish (Corydoras) can also work well, though angelfish at least are predatory and will eat very small fish such as neon tetras.

Notoriously bad community fish include the red-tailed black shark, the sucking loach Gyrinocheilus aymonieri, and many types of cichlid and catfish. These fish are often aggressive and/or predatory, so are best kept in species tanks or in carefully constructed communities with other robust species.

Water chemistry

Most freshwater aquarium fish do well in water that is soft to moderately hard, and has a pH between 6 and 8; the notable exceptions are the Poeciliidae such as guppies and mollies, which should generally only be kept in hard, alkaline water.

Brackish water aquaria are another special case and need their own community tanks. While a few freshwater and marine fish can adapt to brackish water, most cannot [1].

External links

• Age of Aquariums Promotes responsible fishkeeping internationally since 1997.
• Wet Web Media - A good site for general aquarium information
• Can I Keep It? and More Can I Keep It? Two freeware programs for comparing the compatibility of different freshwater fish (Mac/Windows)