Cichlids are fish from the family Cichlidae in the order Cichliformes. Traditionally Cichlids were classed in a suborder, the Labroidei, along with the wrasses (Labridae), in the order Perciformes, but molecular studies have contradicted this grouping. On the basis of fossil evidence, it first appeared in Tanzania during the Eocene epoch, about 46–45 million years ago. The closest living relative of cichlids is probably the convict blenny, and both families are classified in the 5th edition of Fishes of the World as the two families in the Cichliformes, part of the subseries Ovalentaria. This family is large, diverse, and widely dispersed. At least 1,650 species have been scientifically described, making it one of the largest vertebrate families. New species are discovered annually, and many species remain undescribed. The actual number of species is therefore unknown, with estimates varying between 2,000 and 3,000.
An electric fish is any fish that can generate electric fields. Most electric fish are also electroreceptive, meaning that they can sense electric fields. The only exception is the stargazer family (Uranoscopidae). Electric fish, although a small minority of all fishes, include both oceanic and freshwater species, and both cartilaginous and bony fishes.
Electroreception and electrogenesis are the closely related biological abilities to perceive electrical stimuli and to generate electric fields. Both are used to locate prey; stronger electric discharges are used in a few groups of fishes to stun prey. The capabilities are found almost exclusively in aquatic or amphibious animals, since water is a much better conductor of electricity than air. In passive electrolocation, objects such as prey are detected by sensing the electric fields they create. In active electrolocation, fish generate a weak electric field and sense the different distortions of that field created by objects that conduct or resist electricity. Active electrolocation is practised by two groups of weakly electric fish, the Gymnotiformes (knifefishes) and the Mormyridae (elephantfishes), and by Gymnarchus niloticus, the African knifefish. An electric fish generates an electric field using an electric organ, modified from muscles in its tail. The field is called weak if it is only enough to detect prey, and strong if it is powerful enough to stun or kill. The field may be in brief pulses, as in the elephantfishes, or a continuous wave, as in the knifefishes. Some strongly electric fish, such as the electric eel, locate prey by generating a weak electric field, and then discharge their electric organs strongly to stun the prey; other strongly electric fish, such as the electric ray, electrolocate passively. The stargazers are unique in being strongly electric but not using electrolocation.
Polypterus senegalus, the Senegal bichir, gray bichir or Cuvier's bichir, and sometimes called the "dinosaur eel", "dinosaur bichir", or "dragon fish" is in the pet trade due to its lungfish-like appearance, which was described as more primitive and prehistoric than other modern fishes. It is a prototypical species of fish in the genus Polypterus, meaning most of its features are held across the genus. It is commonly kept in captivity by hobbyists. They are native from Africa where they are the most widespread species of the genus.
The Mormyridae, sometimes called "elephantfish", are a superfamily of weakly electric fish in the order Osteoglossiformes native to Africa. It is by far the largest family in the order, with around 200 species. Members of the family can be popular, if challenging, aquarium species. These fish have a large brain size and unusually high intelligence.
Peters's elephant-nose fish is an African freshwater elephantfish in the genus Gnathonemus. Other names in English include elephantnose fish, long-nosed elephant fish, and Ubangi mormyrid, after the Ubangi River. The Latin name petersii is probably for the German naturalist Wilhelm Peters. The fish uses electrolocation to find prey, and has the largest brain-to-body oxygen use ratio of all known vertebrates.
The red-bellied piranha, also known as the red piranha, is a type of piranha native to South America, found in the Amazon, Paraguay, Paraná and Essequibo basins, as well as coastal rivers of northeastern Brazil. This fish is locally abundant in its freshwater habitat. They are omnivorous foragers and feed on insects, worms, crustaceans, and fish. They are not a migratory species but do travel to seek out conditions conducive to breeding and spawning during periods of increased rainfall. Red-bellied piranhas often travel in shoals as a predatory defense but rarely exhibit group hunting behavior. Acoustic communication is common and is sometimes exhibited along with aggressive behaviors. They are a popular aquarium fish.
Nimbochromis polystigma is a species of cichlid endemic to Lake Malawi, in the Great Rift Valley system of Africa. This species prefers areas with rock/sand substrate or areas with plentiful vegetation. It can grow to a length of 23 centimetres (9.1 in) TL.
The African brown knifefish, is the only species in the genus Xenomystus of the family Notopteridae. This fish is found in the Chad, Nile, Congo, Ogowe and Niger basins, as well as coastal river basins in Sierra Leone, Liberia, Togo, Benin and Cameroon.
Lepidophagy is a specialised feeding behaviour in fish that involves eating the scales of other fish. Lepidophagy is widespread, having evolved independently in at least five freshwater families and seven marine families. A related feeding behavior among fish is pterygophagy: feeding on the fins of other fish.
Rhamphochromis is a genus of East African haplochromine cichlids endemic to the Lake Malawi basin, also including Lake Malombe, Lake Chilingali, Chia Lagoon and upper Shire River. They mainly occur in offshore open waters, but a few species also near the coast. They are piscivores that typically feed on lake sardines and small utaka cichlids.
The Malawi eyebiter is a species of fish in the family Cichlidae. This predatory cichlid is endemic to Lake Malawi in East Africa.
Marcusenius is a genus of the elephantfish group native to Africa. Its members are highly diverse in size, with the smallest species reaching less than 15 cm (6 in) and the largest more than 1 m (3.3 ft).
Mormyrops is a genus of weakly electric fish in the family Mormyridae from freshwater in Africa. They are characterized by an elongate head measuring twice as long as high, and no teeth on the palate or the tongue. The genus includes the largest member of the mormyrid family, the cornish jack at up to 1.5 m (4.9 ft) in length.
The subfamily Mormyrinae contains all but one of the genera of the African freshwater fish family Mormyridae in the order Osteoglossiformes. They are often called elephantfish due to a long protrusion below their mouths used to detect buried invertebrates that is suggestive of a tusk or trunk. They can also be called tapirfish.
Myomyrus is a genus of elephantfish in the family Mormyridae. Its members reach about 25–30 cm (10–12 in) in length and are restricted to the Congo River Basin in Africa.
Oxymormyrus is a small genus of elephantfish in the family Mormyridae. Its members reach about 25–27 cm (10–11 in) in length and are restricted to the Congo, Campo, Kouilou-Niari, Nyanga and Ogowe river basins in Middle Africa.
Petrocephalus is a genus of ray-finned fish in the family Mormyridae. All the fish species of this genus are endemic to Africa.
Australoheros facetus, formerly Cichlasoma facetum, the chameleon cichlid or chanchito, is a species of cichlid from the subfamily Cichlasomatinae which is native to northern Argentina, Paraguay, Uruguay and southern Brazil.
The Mormyroidea are a superfamily of fresh water fishes endemic to Africa that, together with the families Hiodontidae, Osteoglossidae, Pantodontidae and Notopteridae, represents one of the main groups of living Osteoglossiformes. They stand out for their use of weak electric fields, which they use to orient themselves, reproduce, feed, and communicate.
