Red wolf fish, Erythrinus erythrinus

Dr Sean Evans looks at the Red wolf fish, Erythrinus erythrinus, which is sometimes sold as sp. "Peru".

Fact File
Common name: Red Wolf Fish
Scientific name: Erythrinus erythrinus (Bloch and Schneider, 1801)
Origin: Widespread in Central and South America.
Size: Around 20cm/8".
Diet: Carnivorous and predatory. In the aquarium they will eat mussel, whitebait bloodworm and earthworms. Some will take floating cichlid pellets or sinking catfish pellets, especially if these foods are introduced early to juvenile fish - may become fussier with age.
Water: Not critical - generally very hardy and undemanding. Fairly soft to medium hard and pH around neutral is fine. Temperature around 24C/75F.
Aquarium: A tank size of around 90 x 30 x 38cm/36 x 12 x 15" will be sufficient. These are not overly active fish (except at feeding time) and don't require large tanks. Use a sand or smooth gravel substrate and smooth rocks or pieces of bogwood for dcor. PVC or clay pipes are also favoured hiding places. Securely rooted plants can be included, or use types that can be attached to bogwood, such as Java Fern and Anubias. Floating plants could also be used. Use a tight-fitting cover, as these fish can escape the aquarium.
Sexing: Unknown, but females may be larger and more heavily built.
Breeding: No reports in captivity.
Notes: Aggressive towards its own kind and similar fish, best kept alone. Will eat small fish. Recent studies have shown that different populations of Erythrinus erythrinus have differences in their genetic make-up, and this appears to indicate a species-complex, rather than a single species. It's quite likely that additional species or subspecies may be described. The variant pictured here is often known as the Red sailfin wolf fish, or Erythrinus sp "Peru". The only other species currently assigned in the genus is Erythrinus kessleri.
Availability: Not common, but reasonable availability from more specialist aquatic shops. Often mis-sold as Hoplerythrinus unitaeniatus.
Price: Likely to be 20 or more, increasing for larger specimens.
Dr Sean Evans