Erythrinus

Erythrinus is a genus of ray-finned fish in the family Erythrinidae, commonly known as the wolf tetras. These fish are native to South America, found in freshwater habitats such as rivers, lakes, and swamps. The genus currently contains several described species, with Erythrinus erythrinus being the most well-known.

Wolf tetras are predatory fish, characterized by their elongated bodies, large mouths, and sharp teeth. They are typically dark in color, often with reddish or brownish hues, and can grow to a moderate size. Their diet consists mainly of smaller fish, invertebrates, and amphibians. Due to their predatory nature, they are not generally kept in community aquariums with smaller fish.

Reproduction in Erythrinus species involves external fertilization. Females lay eggs, which are then fertilized by the males. Parental care, if any, varies among species. These fish are adapted to a wide range of aquatic environments, including those with low oxygen levels, due to their ability to gulp air at the surface.

Erythrinus species are of interest to ichthyologists for their evolutionary adaptations and ecological roles within their native ecosystems. While not widely farmed for consumption, they are sometimes encountered in the aquarium trade, though their aggressive tendencies limit their popularity among hobbyists.