BEAUTY FISH

Hybrid cichlids and selective breeding

Some cichlids have been found to hybridise with closely related species quite readily, both in the wild and under artificial conditions.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.

The most ubiquitous aquarium hybrid is perhaps the blood parrot cichlid which is a cross of several species especially those from genus Amphilophus. With a beak-shaped mouth, an abnormal spine, and an occasionally missing caudal fin (known as the "love heart" parrot cichlid), the fish has caused controversy among aquarium enthusiasts. Some has called blood parrot cichlid "the Frankenstein monster of the fish world."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.Both dominant and recessively inherited pigment mutations have been observed for cichlids.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.

Cichlids as aquarium fish

Since 1945, cichlids have become increasingly popular as aquarium fish 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.

The most commonly encountered species in retail aquariums is Pterophyllum scalare from the

Amazon River basin in tropical South America, known in the trade as the "angelfish" . Other popular or readily available species of cichlids include the oscar (Astronotus ocellatus), convict cichlid (Archocentrus nigrofasciatus) and discus (Symphysodon spp.).

Species of cichlid can be kept in aquariums with other fish, however, many cichlids are predatory towards smaller fish.Conversely, some cichlids, such as Apistogramma or Julidochromis spp., can be timid in the aquarium. In such cases the use of dither fish is recommended.

Cichlid

Cichlids (pronounced /ˈsɪklɪd/) are fishes from the family Cichlidae in the order Perciformes. The family Cichlidae, a major family of perciform fish, is both large and diverse. Estima

tes of the number of cichlid species range from 1,900 to 2,200, making it one of the three largest vertebrate families.Cichlids span a wide range of body sizes, from species as small

as 2.5 centimetres (1.0 in) in length (e.g. 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 strong

ly 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 the African Rift Valley lakes of Tanganyika, and Victoria, and Malawi.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.