Phractocephalus

Phractocephalus is a genus of large freshwater catfishes in the family Pimelodidae, native to the river systems of northern South America, particularly the Amazon and Orinoco basins. The genus includes a small number of species, the best known being the red-tailed catfish, Phractocephalus hemioliopterus. Members of this genus are among the largest Neotropical catfishes, with adults capable of reaching about 1.5 to 1.8 meters in length and weighing several tens of kilograms in the wild.

Morphology and identification: They have elongated bodies, a broad flat head, and extremely long barbels that help locate prey in turbid waters. The dorsal and pectoral fins are well developed; an adipose fin is present. Coloration varies, with the red-tailed catfish notable for its striking bright orange-red caudal fin.

Habitat and ecology: They inhabit large rivers and connected floodplains, often in slow-moving or moderately fast waters with leaf litter and soft bottoms. They are primarily bottom-dwelling and nocturnal; diets are omnivorous and opportunistic, including fish, crustaceans, invertebrates, and occasionally plant matter. Reproduction is poorly documented in the wild; spawning is believed to occur during seasonal flooding, with some migration between floodplain habitats.

Relationship to humans: They are popular among sport anglers in their range and feature in the aquarium trade, though their size and long lifespans make them unsuitable for most hobbyists. Habitat degradation and overfishing threaten populations in parts of their range.