Rainbow Wolf Fish (Erythrinus erythrinus)

Rainbow Wolf Fish (Erythrinus erythrinus) known to tropical fish keeping enthusiasts as High Fin Wolf Fish or Red Wolf Fish are found in Brazil, French Guiana, Peru, Trinidad and Tobago,  and Venezuela.

Rainbow Wolf Fish (Erythrinus erythrinus)  are usually found among surface vegetation in the very shallow waters of small river tributaries, swamps, the margins of forest lakes, marshes, pools, and ditches of their range.

The Rainbow Wolf Fish has a modified swim bladder that allows it to breath air and survive in stagnant or oxygen depleted waters and like “walking catfish” they have been know to travel short distances over land when their native waters begin to dry up.

Rainbow Wolf Fish are carnivorous predators that sport a mouth filled with sharp teeth.   They show absolutely no fear and will viciously strike at any object introduced into their tank.

Rainbow Wolf Fish (Erythrinus erythrinus)

Rainbow Wolf Fish vary in color depending on locality.  In general they have a light to dark brown body color with a wide lateral line that runs from the eye to the caudal fin.  Their set back dorsal and caudal fins are brown tinged with yellow to reddish orange and their pelvic and ventral fins are translucent white to yellow.  Although most Rainbow Wolf Fish have bone to white undersides, a Peruvian variant has a brightly colored orange belly.   Adult females can be identified by their more slightly rounded bellies.

A species of juvenile Rainbow Wolf Fish in Grench Guiana has a color pattern that mimics a species of female Rivulus Killifish.    Male Rivulus are attracted to the mimic “female” and are promptly gobbled up by the Wolf Fish.  The strategy ceases as the Erythrinus grows into adulthood.

Genetic studies of different populations have determined that Erythrinus erythrinus is a species complex and not just a single species.  One other recognized species (Erythinus kessleri) that grows to a maximum length of 7.5″ is found in the Itapicuru River in Brazil and is virtually unheard of by tropical fish keeping enthusiasts.

Erythrinus erythrinus can be housed with similarly sized South American species in a large tank but because of their ferocity as adults, they are better suited to a densely planted, dimly lit, single species aquarium of at least 55 gallon capacity with a sandy or fine gravel substrate, plenty of floating plants, and plenty of hiding places in the form or driftwood or bogwood roots.

Erythrinus erythrinus  are extremely intolerant of conspecifics and like male Bettas, will often fight to the death.  Smaller fish introduced into the tank will be quickly eaten, so be careful when selecting tank mates if you plan on keeping them in a community environment.

Rainbow Wolf Fish are excellent jumpers and require a tightly fitting tank to prevent them from escaping.  Although they can handle a wide variety of water parameters, they need a good filtration system with little to no water movement to keep them happy.

There are no reports of Rainbow Wolf Fish being successfully bred in an aquarium environment.  This is probably due to their behavior towards conspecifics.

In their natural environment, Rainbow Wolf Fish feed on insects, worms, and other fish.  In an aquarium environment, they require live or frozen earthworms, mussels, prawn, shrimp, and white fish.  They will usually refuse freeze dried or prepared carnivore pellets or flakes but they have been known to accept them when gradually offered over time.  Because of the possibility of transmitting parasites or other diseases into the tank, refrain from feeding them live “feeder fish”.

Rainbow Wolf Fish are not often available to tropical fish keeping enthusiasts but on occasion, specialty fish shops, importers, and online fish auction sites do have them available as juveniles at  2 to 4 inches in length and occasionally as adults.

Rainbow Wolf Fish (Erythrinus erythrinus)

Minimum Tank Size: 55 gallons
Care Level: Difficult
Temperament: Highly Aggressive
Aquarium Hardiness: Hardy
Water Conditions: 72-79°F, 2-25°H, pH 5.5-7.5
Max. Size:
Color Form: Red, Brown
Diet: Carnivore
Compatibility: Single species
Origin: Peru, Brazil, Venezuela
Family: Erythrinidae
Lifespan: 4-10 years
Aquarist Experience Level: Advanced