Erythrinidae

Erythrinidae is a family of freshwater ray-finned fishes in the order Characiformes, native to tropical and subtropical regions of South America. Commonly referred to as erythrinids or wolf fishes, they are predatory species that rely on ambush tactics and rapid strikes to catch prey. The family is distributed mainly in South American river basins, including the Amazon, Orinoco, and Paraná systems, as well as associated floodplains and tributaries.

Taxonomy and genera within Erythrinidae include several lineages, notably Erythrinus, Hoplias, and Hoplerythrinus. These genera group species that share a robust, elongated body plan and a large mouth equipped with sharp teeth. Coloration and markings vary by species, ranging from olive or gray to more vividly banded patterns, often providing camouflage in submerged vegetation or debris.

Ecology and behaviorally, erythrinids are primarily piscivorous and opportunistic predators, feeding on smaller fish, amphibians, and invertebrates. They typically inhabit slow-moving or standing freshwater with plenty of cover, such as submerged roots, fallen wood, or aquatic vegetation. Adults are usually solitary and territorial, and some species can be aggressive toward conspecifics or other fish when guarding territories or during breeding.

Reproduction involves sexual reproduction with seasonal breeding tied to rainfall and rising water levels in many basins. Eggs are often laid in nests or attached to vegetation and debris, with limited parental care. Fry emerge as small carnivores and grow into large, powerful predators.

Conservation and human interactions vary by species. While many erythrinids are not globally threatened, localized populations can be affected by habitat destruction, water pollution, and overfishing. They are sometimes valued for sport fishing and, less commonly, kept in aquariums, though their size and temperament limit aquarium use.