Characidae

Characidae is a family of freshwater fishes in the order Characiformes, commonly called characins or tetras. It is one of the largest and most diverse groups of Neotropical fishes, with hundreds of described species distributed mainly across Central and South America, and in some southern North American streams. Members inhabit a broad range of freshwater habitats, from fast rivers to slow, shaded blackwater streams and flooded forests.

Most characids have a slender, laterally compressed body, a single dorsal fin, and an adipose fin in many species. They display a wide array of coloration and sizes, from small, iridescent schooling tetras to more robust species. Diet is varied, including insects, crustaceans, plant material, and detritus; several species are omnivorous. In the wild, characids are typically diurnal and form schools, a behavior that is often mirrored in the aquarium hobby. Well-known aquarium representatives include neon tetra (Paracheirodon innesi) and cardinal tetra (Paracheirodon axelrodi).

Reproduction in Characidae generally involves external fertilization, with eggs laid on vegetation or substrate; many species are egg scatterers, while others have more specialized spawning behaviors. The family is taxonomically complex and has undergone substantial revision, with numerous genera previously placed in Characidae reassigned to other families within Characiformes, such as Serrasalmidae, or moved to distinct Characiform lineages. As a result, the circumscription of Characidae continues to evolve. Conservation status varies widely by species; habitat degradation, pollution, and collection for the aquarium trade threaten some taxa, while others remain widespread and common.