Tilapias are small to medium sized African fish that
are the focus of major fishing and aquaculture efforts. They are
members of the family Cichlidae and resemble perch or bass in general
shape, but as with all cichlids they have a single, long dorsal
fin instead of two, as is typical of perch and bass. They inhabit
a variety of fresh and, less commonly, brackish water habitats from
shallow streams and ponds through to rivers, lakes, and estuaries.
Most tilapias are omnivorous with a preference for soft aquatic
vegetation and detritus.
Tilapia are native to Africa and the Levant, but have been widely
introduced into tropical fresh and brackish waters around the world.
Some introductions, as in Florida and Texas, were planned, most
likely caused by purposeful introductions by government agencies
to control other invasive aquatic plants, etc. . More often,
however, the fish have been introduced deliberately for commercial
or industrial scale aquaculture. Because tilapia are large, fast
growing, highly fecund, and tolerate a wide variety of water conditions
(even marine conditions), once introduced into a habitat they generally
establish themselves very quickly. In many places, particularly
Florida and Australia, feral populations of tilapia have had detrimental
effects on ecosystems. On Rennell Island, the Rennell Island Teal
became extinct after introduced Oreochromis mossambicus multiplied
in the absence of predators (the local population did not fancy
the fish); the ducklings of the small waterbird were simply eaten
away by the tilapia.
The larger Tilapia species are generally not viewed as good aquarium
fish because they eat plants and tend to be very disruptive, digging
up the substrate and fighting with other fish. Only the smaller
west Afrian species, such as Tilapia joka, and those species from
the crater lakes of Cameroon have become at all popular among aquarists.
On the other hand, they are hardy and easy to keep, provided they
get enough space. They mix well with non-territorial cichlids, armoured
catfish, tinfoil barbs, garpike, and other robust but peaceful fish.
Some species, including Tilapia buttikoferi, Tilapia rendalli, Tilapia
joka, and the brackish water Sarotherodon melanotheron melanotheron,
are attractively patterned and decorative fish.
Broadly speaking, tilapias of the genus Tilapia are substratum spawning
cichlids, meaning that the fish form pairs, lay the eggs on the
substrate, and then guard the eggs and fry. Tilapias of the genus
Sarotherodon are mouthbrooders, with either both parents or just
the male looking after the eggs or fry. Finally, tilapias of the
genus Oreochromis, by contrast, are also mouthbrooders but in this
case it is normally the female that looks after the eggs and fry.
Groups of male Oreochromis form leks where they compete with one
another for opportunities to mate with the females. Beyond this,
they show no interest in the eggs or fry and do not extend any broodcare
to their offspring at all.
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