Tetra is the common name of many small freshwater characiform fishes. Tetras come from Africa, Central America, and South America, belonging to the biological family Characidae and to its former subfamilies Alestidae and Lebiasinidae. The Characidae are distinguished from other fish by the presence of a small adipose fin between the dorsal and caudal fins. Many of these, such as the neon tetra, are brightly colored and easy to keep in captivity. Consequently, they are extremely popular for home aquaria.
Hyphessobrycon is a genus of freshwater fish in the family Characidae. These species are among the fishes known as tetras. The genus is distributed in the Neotropical realm from southern Mexico to Río de la Plata in Argentina. Many of these species are native to South America; about six species are from Central America and a single species, H. compressus is from southern Mexico.
Astyanax is a genus of freshwater fish in the family Characidae of the order Characiformes. Some of these fish, like many of their relatives, are kept as aquarium pets and known collectively as tetras. With around 150 described species and new ones being described yearly, this genus is among the largest of the entire order; Hyphessobrycon also has more than 145 species and which one is larger at any one time depends on whether more species have been recently described in one or the other. The blind and colorless cave tetra of Mexico is a famous member of the genus, but its taxonomic position is disputed: Some recognize it as part of the Mexican tetra and this is supported by phylogenetic evidence, but others recognize the cave form as a separate species, A. jordani.
African tetras are a group of characiform fish exclusively found in Africa. This family contains about 18 genera and 119 species. Among the best known members are the Congo tetra, and African tigerfish.
Mastacembelus is a genus of many species of spiny eel fish from the family Mastacembelidae. They are native to Africa and Asia. Most are found in rivers and associated systems, but there are also species in other freshwater habitats and a particularly rich radiation is found in the Lake Tanganyika basin with 15 species. A few species can even occur in brackish water.
Hepsetus is a genus of African fishes, the African pikes or African pike characins, in the order Characiformes. It is the sole genus in the family Hepsetidae. It was long believed that only a single widespread species existed, H. odoe, but studies in 2011–2013 have shown that this species is restricted to parts of West and Central Africa. The well-known species of southern Africa, including Kafue River, is Hepsetus cuvieri. These predatory fish reach up to 44 cm (17 in) in length.
Synodontis is the largest genus of mochokid catfishes. It is the biggest genus within the 10 genera and 190 different species in the family Mochokidae. Synodontis has over 131 different species within the genus. Synodontis are also known as squeakers, due to their ability to make stridulatory sounds through their pectoral fin spines when handled or disturbed. Synodontis make a sound that sounds like squeaking by rubbing their spines together. They do this when they have been frightened or when they become angry. Synodontis may also squeak when they are taken out of the water. These catfish are small- to medium-sized fish with many species exhibiting attractive spotted markings. Some species are also known for naturally swimming belly-up, earning the name upside-down catfish. Some of these species are Synodontis contractus and Synodontis nigriventris. While some of these species are known to swim upside down, another species, Synodontis multipunctatus, is a brood parasitic cuckoo catfish,there are two other species Synodontis petricola and Synodontis grandiops are also called brood parasitic cuckoo catfish.
Haplochromis is a ray-finned fish genus in the family Cichlidae. It has been used as the default "wastebin taxon" for Pseudocrenilabrinae cichlids of the East African Rift, and as such became the "largest" fish "genus". Many of these cichlids are popular aquarium fishes; like similar Haplochromini they are known as "haplos", "happies" or "haps" among aquarium enthusiasts.
Alestes is a genus in the family Alestidae, known as the "African Characidae" as they are found exclusively on that continent. As suggested by that name, they Alestidae was formerly included in Characidae. Myletes is a synonym of Alestes, but the former name has historically also been used for various South American serrasalmines.
Chrysichthys is a genus of claroteid catfishes native to Africa. Two fossil species are known. Chrysichthys macrotis, Van Neer, 1994, is known from the Miocene-Pliocene of the Albertine Rift in Uganda and Chrysichthys mahengeensis, Murray & Budney, 2003, is known from the Eocene of Mahenge, Tanzania.
Distichodus is a genus of freshwater fish in the family Distichodontidae found in 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).
Micralestes is a genus of African tetras. There are currently 17 species in this genus.
Labeobarbus is a mid-sized ray-finned fish genus in the family Cyprinidae. Its species are widely distributed throughout eastern Africa and especially southern Africa, but also in Lake Tana in Ethiopia. A common name, in particular for the southern species, is yellowfish. The scientific name refers to the fact that these large barbs recall the fairly closely related "carps" in the genus Labeo in size and shape. As far as can be told, all Labeobarbus species are hexaploid.
Cyphomyrus is a genus of ray-finned fish in the family Mormyridae, the freshwater elephantfishes.
Phenacogrammus is a genus of African tetras found in Middle Africa.
Hemigrammus is a genus of freshwater fish in the family Characidae native to South America and commonly seen in the aquarium trade. These are medium-small tetras where the largest species reach up to around 11 cm (4.3 in).
Iguanodectes is a genus of freshwater fish found in tropical South America, with eight currently described species. They are all small tetras, none longer than 5 inches, and often have attractive silvery or striped scales, which makes them a target for the ornamental fish industry. Alongside the genus Piabucus, it is in the subfamily Iguanodectinae, which in turn is in the family Iguanodectidae. The genus Bryconops, which is also in Iguanodectidae, makes up a sister clade to Iguanodectinae.
Nannocharax is a genus of distichodontid freshwater fishes found in Africa.
Enteromius is a genus of small to medium-sized cyprinid fish native to tropical Africa. Most species were placed in the genus Barbus.
