cichlid n : freshwater fishes of tropical America and Africa and Asia similar to American sunfishes; some are food fishes; many small ones are popular in aquariums [syn: cichlid fish]

English

Pronunciation

• /ˈsɪklɪd/

Noun

1. Any of many tropical fish, of the family Cichlidae, popular as aquarium fish.

Translations

Swedish

Noun

cichlid

Cichlids () are fishes from the family Cichlidae in the order Perciformes. The family Cichlidae, a major family of perciform fish, is both large and diverse. There are at least 1300 scientifically described species, making it one of the three largest vertebrate families. Numerous new species are discovered annually, and many species remain undescribed. The actual number of species is therefore unclear, with estimates varying between 1300 and 3000 species, and one source suggesting 1900 species. Cichlids span a wide range of body sizes, from species as small as 2.5 centimetres (1.0 in) in length (e.g. female Neolamprologus multifasciatus ) to much larger species approaching 1 metre (3 ft) in length (e.g. Boulengerochromis and Cichla). As a group, cichlids exhibit a similarly wide diversity of body shapes, ranging from strongly laterally compressed species (such as Altolamprologus, Pterophyllum, and Symphysodon) through to species that are cylindrical and highly elongate (such as Julidochromis, Teleogramma, Teleocichla, Crenicichla, and Gobiocichla). Generally, however, cichlids tend to be of medium size, ovate in shape and slightly laterally compressed, and generally very similar to the North American sunfishes in terms of morphology, behaviour, and ecology.

Many cichlids, particularly the tilapias, are important food fishes, while others are valued game fish (eg. Cichla species). Many species, including the angelfish, oscars, and discus, are also highly valued in the aquarium trade. Cichlids are also the family of vertebrates with the largest number of endangered species, most of these found in the haplochromine group. Cichlids are particularly well known for having evolved rapidly into a large number of closely related but morphologically diverse species within large lakes, particularly Tanganyika, Victoria, Malawi, and Edward, . The diversity of cichlids in the African Great Lakes is important for the study of speciation in evolution. Many cichlids that have been accidentally or deliberately released into freshwaters outside of their natural range have become nuisance species, for example tilapia in the southern United States.

Anatomy and appearance

Cichlids are astonishingly diverse in terms of diet. Many are primarily herbivores feeding on algae (e.g. Petrochromis) and plants (e.g. Etroplus suratensis) and small animals, particularly invertebrates, are only a small part of their diet. Some cichlids are detritivores and eat all types of organic material; among these species are the tilapiines of the genera Oreochromis, Sarotherodon, and Tilapia.

Other cichlids are predatory and eat little if any plant matter. These include generalists that catch a variety of small animals including other fishes and insect larvae (e.g. Pterophyllum), as well as variety of specialists. Trematocranus is a specialised snail-eater, while Pungu maclareni feeds on sponges. A number of cichlids feed on other fish, either whole or in part. Crenicichla are stealth-predators that lunge at small fish that pass by their hiding places, while Rhamphochromis are open water pursuit predators that chase down their prey. Paedophagous cichlids such as the Caprichromis species eat other species' eggs or young (in some cases ramming the heads of mouthbrooding species to force them to disgorge their young). Among the more unusual feeding strategies are those of Corematodus spp., Docimodus evelynae, Plecodus, Perissodus and Genyochromis species, which feed on scales and fins of other fishes, a behaviour known as lepidophagy along with the death mimicking behaviour of Nimbochromis and Parachromis species, which lay motionless, luring small fish to their side prior to ambush.

Scientists believe it is this wide adaptability of feeding styles that has helped cichlids to inhabit such a wide range of habitats. It is largely the pharyngeal teeth (teeth in the throat) that allows the cichlids so many 'niche' feeding behaviours, i.e. the jaws may be used to hold or pick food, while the pharyngeal teeth are used to crush what was harvested.

Reproduction

Brood care

All species show some form of parental care for both eggs and larvae, often extended to free-swimming young until they are several weeks or months old. Species of this family have highly organized breeding activities.), and at least two types of mouthbrooding, ovophile mouthbrooding and larvophile mouthbrooding.

Open or substrate brooding cichlids lay their eggs in the open on rocks, leaves or logs. Examples of open brooding cichlids include Pterophyllum, Symphysodon spp and Anomalochromis thomasi. In general, brooding biparental substrate brooding cichlids usually engage in differing roles with regard to protection and raising of the fry. Most commonly, the male parent patrols the pair's territory and repels intruders, while females more intensively tend the brood, fanning water over the eggs, removing infertile eggs and leading the school of fry while foraging. Despite this, both sexes are able to perform the full range of parenting behaviours. Comparably, the fry of Neolamprologus brichardi, a species that commonly lives in large groups, are protected not only by the adults, but also by older juveniles from previous spawns. Ovophile mouthbrooders incubate their eggs in their mouths as soon as they are laid, and frequently continue to brood free-swimming fry in their mouths for several weeks. Examples of ovophile mouthbrooding cichlids include many of the cichlids endemic to the Rift Valley lakes (Lake Malawi, Lake Tanganyika and Lake Victoria) in east Africa eg: Maylandia, Pseudotropheus and Tropheus along with some south american cichlids such as Geophagus steindachneri. Larvophile mouthbrooding species lay the eggs in the open, or in a cave and upon hatching take the larvae into the mouth. Examples include some variants of Geophagus altifrons, some Aequidens, Gymnogeophagus and Satanoperca species. This method is common and appears to have evolved independently in several groups of African cichlids.

Endangered cichlids

According to the 2007 International Union for Conservation of Nature and Natural Resources red list 156 cichlid species are currently listed as vulnerable, 40 species are listed as endangered, while 69 species are listed as critically endangered. Six species, Haplochromis ishmaeli, Haplochromis lividus, Haplochromis perrieri, Paretroplus menarambo, Platytaeniodus degeni and Yssichromis sp. nov. 'argens' are extinct in the wild, while at least 39 species, most from the genus Haplochromis, have become extinct since the early 1990s.

Lake Victoria

Because of the introduced Nile perch (Lates niloticus) and water hyacinth, deforestation causing siltation of water, and overfishing, many species of Lake Victoria cichlids have been wiped out or drastically reduced in the wild. By around 1980, fisheries of the lake yielded only 1 percent cichlids from all the catch, a drastic decline from 80 percent in the earlier years.]] As many as three hundred species or about two-thirds of the endemic cichlids, especially the ones that feed in the open bottom of the lake, became endangered or extinct. Some surviving cichlids, however, have adapted to the new threats by becoming smaller or hybridising with other species. The most important food cichlids, however, are the tilapiines of North Africa. Fast growing, tolerant of stocking density, and highly adaptable, tilapiine species have been introduced and farmed extensively in many parts of Asia and are increasingly common in other parts of the world. Production of farmed tilapia, at about 1.5 million tons annually with an estimated value of US$1.8 billion, is about equal to that of salmon and trout. Unlike carnivorous salmon and trout, however, tilapia are mostly omnivorous and can feed on algae or any plant-based food. This reduces the cost of tilapia farming greatly and makes tilapia the ideal "aquatic chickens" of the trade. Other cichlids preferred by anglers include the oscar, Mayan cichlid (Cichlasoma urophthalmus), and jaguar guapote (Parachromis managuensis). Cichlids are ideally suited as aquarium fish as many are small to medium-sized, easy to feed with a range of prepared fish foods, breed readily, and practice brood care, in captivity. This is not particularly unusual, having been observed among other groups of fishes, such as European cyprinids. What is unusual is the extent to which cichlid hybrids have been put to commercial use, in particular as food fish and as aquarium fish. The red strain of tilapia hybrid, for example, is often preferred in aquaculture as they have faster growth rates. Tilapia hybridisation is also used to produce all-male populations to control stock density and prohibit reproduction in ponds. Another notable hybrid, the flowerhorn cichlid, was very popular in some parts of Asia from 2001 until late 2003 and is believed to bring good luck to its owner. The popularity of the flowerhorn cichlid declined in 2004, resulting in many flowerhorn cichlids being released into the rivers and canals of Malaysia and Singapore where they pose a threat to endemic animal communities. Numerous cichlid species have also been the subject of selective breeding programmes to develop new ornamental strains for the aquarium trade. The most intensive selective breeding programs have involved angelfish and discus and many mutations that effect both colouration and finnage are known. Many other cichlids have been selecively bred for albino, leucistic and xanthistic pigment mutations including oscars, convicts and Pelvicachromis pulcher. In convict cichlids, for example, a leucistic colouration is recessively inherited, while in Oreochromis niloticus niloticus red colouration is caused by an dominantly inherited mutation.

These efforts at selectively breeding may, however, have unintended consequences. For example, some selectively bred strains of Mikrogeophagus ramirezi have health and fertility problems. Similarly, the inbreeding involved in selective breeding programmes can cause severe physical abnormalies such as the notched phenotype in angelfish.

Genera

As of 2006, there were some 220 genera:

Images of cichlids

Main gallery: Cichlid images

Mikrogeophagus ramirezi), male in front, female behind. Many cichlids form strong pair bonds while breeding. shell-brooding cichlid of the genus Lamprologus from Lake Tanganyika in East Africa flowerhorn cichlid is a man-made hybrid that has recently gained popularity among aquarists, particularly in Asia.

See also

• Perciformes
• Aquaculture
• Fishkeeping
• Aquarium

References

Further reading

• Barlow, G. W. (2000). The Cichlid fishes. Cambridge MA: Perseus Publishing.

  National Museum of Natural History, Washington, D.C., 2004-05-11).

External links

• Lost African Lake Spawned Fish Diversity "Beyond Belief" Discussing the biodiversity of cichlids.
• The Cichlid Fishes of Lake Malawi by Dr. Michael Oliver.
• An incomplete listing of cichlid genera and species, with phylogenetic context
• Cichlid Room Companion by Juan Miguel Artigas Azas.