Characiformes is an order of ray-finned fish, comprising the characins and their allies. Grouped in 24 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.
Characidae, the characids or characins, is a family of freshwater subtropical and tropical fish belonging to the order Characiformes. The name "characins" is a historical one, but scientists today tend to prefer "characids" to reflect their status as a, by and large, monophyletic group. To arrive there, this family has undergone much systematic and taxonomic change. Among those fishes remaining in the Characidae currently are the tetras, comprising the very similar genera Hemigrammus and Hyphessobrycon, as well as a few related forms, such as the cave and neon tetras. Fish of this family are important as food in several regions, and also constitute a large percentage of captive freshwater aquarium fish species.
Acestrorhynchus is a genus of characiform fish found only in fresh water in South America, the sole genus in the family Acestrorhynchidae. Their greatest diversity is in the Orinoco and Amazon basins.
The Anostomidae are a family of ray-finned fishes that belong to the order Characiformes. Closely related to the Chilodontidae and formerly included with them, the Anostomidae contain about 150 described species. Commonly known as anostomids, they are found in freshwater habitats from the Río Atrato in northernmost South America to warm-temperate central Argentina; they are of Amazon origin, with few found west of the Andes. Their scientific name approximately means "mouth on top", from Ancient Greek áno- (ἄνω) "up" + stóma (στόμᾶ) "mouth", in reference to the arrangement of these fishes' mouth opening.
Nannostomus is a genus of fish belonging to the characin family Lebiasinidae. All of the species in this genus are known as pencil fish, a popular name that was initially only applied to two species in the 1920s, Nannostomus unifasciatus and Nannostomus eques, by the late 1950s however, the term would be applied to all members of the genus. Several species have become popular aquarium fish due to their attractive coloration, unique shape, and interesting demeanor.
Franz Steindachner was an Austrian zoologist, ichthyologist, and herpetologist. He published over 200 papers on fishes and over 50 papers on reptiles and amphibians. Steindachner described hundreds of new species of fish and dozens of new amphibians and reptiles. At least seven species of reptile have been named after him.
The Ctenoluciidae, also known as pike-characins, are a small family of freshwater fishes from Panama and South America.
Roeboides is a genus of characins from Central and South America. These fish, among other characteristics, are small, are typically translucent, and have a rhomboid shape.
Pristella maxillaris is a species of characin in the genus Pristella, and is commonly known as the X-ray fish or X-ray tetra because of its translucent body.
Hepsetus odoe, the African pike characin, is a predatory freshwater characin belonging to the family Hepsetidae. It was formerly considered that there was a single species of Hepsetus pike characin but recent studies have led to the species being split and Hepsetus odoesensu stricto is the west African representative of the group.
Cheirodon is a genus of characins occurring in South America. Of the 10 currently described species; one, C. jaguaribensis, is placed here as a convenience, as its actual position in Characidae is unknown.
Axelrodia is a genus of small characin from the Amazon Basin and Meta River in South America, with three currently described species:
Macropsobrycon is a genus of characins from eastern South America. The currently described species in this genus are:
Parapristella is a genus of characins found in northern South America. Currently, two species are described in this genus:
Prionobrama is a genus of characins found in tropical South America, with two currently described species:
Pseudocheirodon is a genus of characins found in southern Central America. There are currently two described species in this genus.
Roeboexodon is a genus of characins from tropical South America, with two currently recognized species:
Boulengerella is a genus of pike-characins from tropical South America, found in the Amazon Basin, Orinoco, and rivers of the Guiana Shield. Boulengerella was named after the Belgian ichthyologist George Albert Boulenger. The currently described species are:
Hydrolycus is a genus of large dogtooth characins from tropical South America, where found in the Amazon and Orinoco basins, as well as rivers of the Guianas. The genus includes the largest dogtooth characins, reaching up to 1.17 m (3.8 ft) in length. They have long, pointed teeth used for spearing their prey, generally smaller fish. In a study of the stomachs of 45 individuals, most were empty, but among the remaining the prey fish were 15–50% of the length Hydrolycus itself.
Ctenolucius hujeta, also known as silver gar, rocket gar, hujeta gar and freshwater barracuda, is a slender, medium-sized freshwater fish found in Venezuela and Colombia, where it is known as "agujeta"; Spanish for "shoelace".
