Fish, Tanks and Ponds

Fish, Tanks and Ponds
A comprehensive guide to fish

Arnoldichthys spilopterus

African red-eyed tetra

African red-eyed tetra, Arnoldichthys spilopterus
Photos by Andy Rapson


Arnoldichthys: Because of Johann Pane Arnold, born in Germany, 1869-1952

General Notes:

African red-eyed tetra, Arnoldichthys spilopterus should be kept in groups of at least six or seven individuals in order to feel secure and behave more naturally. They are quite boisterous active fish which makes them unsuitable for housing with shy retiring species.


Omnivore with a preference for small live food. In the wild these fish will eat worms, insects and crustaceans. In captivity they will normally accept flake, small pellets are accepted suitably sized live or frozen food which should form part of the the fishes regular diet rather than be seen as a treat.


Arnoldichthys spilopterus can be difficult because the sexes are almost identical but the main differences can be seen on the anal fin which has a translucent appearance with black spot on rays beneath adipose fin in females, while in males the anal fin is lemon yellow (sometimes red-yellow) with 5 dark or black bands and colored margin.


Arnoldichthys spilopterus is fairly easy to get to spawn in the aquarium and if in good condition they will probably spawn quite regularly in a community tank. But the eggs won't survive due to predation. To breed this fish successfully you will need a separate aquarium with lots of fine leaved plants tied in bunches to act as spawning mops. Spawning can go on for a long time and the parents will eat some of their own eggs but a healthy well conditioned female is capable of laying up to 1,000 eggs in a single spawning so the losses are unimportant. After spawning remove the parents and the eggs will hatch after 30 - 36 hours depending on the temperature. When the fry become free swimming they can be fed on using a commercial liquid fry food initially and once big enough they can move on to newly hatched brine shrimps and then finely crushed flake food.

Wild status

Populations of Arnoldichthys spilopterus are found in fewer than ten locations and they are facing loss of habitat due to the oil industry and human encroachment. Because of this wild populations are listed as Vulnerable by the ICUN Red List of threatened species

Information at a glance

pH: 6.5 - 8
dGH: 5 - 19
Temperature: 23 - 28°C (74 - 82°F)
Lighting: Any. None when breeding
Diet: Omnivore
Size: 9cm (3.5in)
Min tank size: 100 litres
Difficulty level: Easy
Aquarium type: Community
Swimming level: All levels

Distribution and habitat

distribution map for African red-eyed tetra

Origin: Africa: lower Niger and Ogun rivers in Nigeria

Habitat: Rivers and streams


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Alestidae
Genus: Arnoldichthys
Species: A. spilopterus Boulenger 1909

Common name:
African red-eyed tetra

Synonyms: Petersius spilopterus