A species for the specialist, E. erythrinus is also known as the rainbow wolf fish or red hi-fin wolf fish. It is quite variable in colour and pattern depending on collection locality. There is a variant from Peru that has a bright orange belly. Recent studies have highlighted genetic differences in these different populations, suggesting that E. erythrinus is actually a species complex, rather than a single species. There is currently one other recognised species in the genus, E. kessleri, but it’s virtually unheard of in the hobby.All the variants have a modified swim bladder that acts as an accessory breathing organ, allowing the fish to survive in oxygen-deficient and stagnant waters. It’s also been known to travel over land for short distances to new habitats when seasonal waters begin to dry up.Interestingly, in French Guiana, juvenile specimens are known to mimic the colour pattern of the female of a particular species of Rivulus killifish, which shares its habitat. Male Rivulus are attracted to the mimic, only to meet with an untimely demise. As the Erythrinus grows it develops more colour and ceases this strategy.