Erythrinus erythrinus, also known as the rainbow wolf fish or red hi-fin wolf fish, is a species that requires specialized care. It exhibits a wide range of colors and patterns, which vary depending on its collection locality. For instance, a variant from Peru has a bright orange belly. Recent studies have revealed genetic differences in different populations, indicating that E. erythrinus might be a complex of species, rather than a single species. Although the genus contains only one other recognized species, E. kessleri, it is rare in the aquarium trade.
All variants of E. erythrinus have a modified swim bladder that functions as an accessory breathing organ, enabling them to survive in oxygen-deficient and stagnant waters. Interestingly, in French Guiana, juvenile specimens of the fish are known to mimic the color pattern of female Rivulus killifish sharing their habitat. Male Rivulus are attracted to the mimic, only to meet with an untimely demise. As Erythrinus erythrinus grows and matures, it develops more colors and ceases this strategy.