Fish, Tanks and Ponds

Fish, Tanks and Ponds
A comprehensive guide to fish

Thayeria boehlkei

Black line penguin tetra

Black line penguin tetra, Thayeria boehlkeiBlack line penguin tetra, Thayeria boehlkei
Photos by Andy Rapson

General Notes:

Although good community fish in the right setting a little care should be taken with this species. Keep a larger than normal group of these fish of at least eight individuals this eliminates fin nipping which can occur if to few are kept. Don't put temptation in their path, don't keep black line penguin tetras with guppies, Siamese fighters, angelfish or any other fish which has long or flowing fins. When in the right setting as outlined above black line penguin tetras are great community fish. They are lively with lots of interaction among their group and they are easy to care for as well as being very hardy.


Wild black line penguin tetras feed on worms, insects and crustaceans. Try to reflect this in their diet by offering lots of suitably sized live or frozen food such as blood worms, glass worms, daphnia, cyclops and brine shrimps. Using a good quality flake food with these will ensure a good balanced diet.


Adult females have a fuller and more rounded abdomen.


Black line penguin tetras are one of the easier characins to breed. Water changes seem to encourage spawning activity. Black line penguin tetras have relatively large broods and a single healthy adult female may produce as many as 3,000 eggs in one brood, keep this in mind if you spawn them as a group rather than a pair. Use a standard set up for breeding tetras.

Use a separate aquarium filled with soft acidic aged water and containing a small air powered sponge filter and something to act as a spawning mop such as a bunch of fine leaved plants tied in to a bunch for example. Keep the tank away from direct light and in very dim conditions because both eggs and fry of this species are light sensitive. Introduce a well conditioned pair in the evening and they will probably spawn at dawn. After spawning remove the parents to prevent them from eating all their eggs. The eggs hatch after about 30 hours but it will be another three or four days before the fry become free swimming. Add a commercially available liquid fry food to the tank about a day or so before the fry become free swimming as this will encourage the growth of infusoria which the fry can eat but don't add to much and pollute the water. Carry on using the liquid food or similar until the fry are large enough to take micro worms or newly hatched brine shrimps. Black line penguin tetras can be bred as a pair or in a group. If you breed them in a group be aware that you will have a very large number of fry which will require a great deal of space to raise and dealers won't thank you if you flood the local market with these fish and they end up stuck with them.

Wild status

The wild population of T. boehlkei has not been evaluated but the species is bred commercially and all specimens offered for sale will have been bred in captivity.

Information at a glance

pH: 6 - 7.5
dGH: 4 - 15
Temperature: 22 - 28°C (72 - 82°F)
Diet: Omnivore
Size: 3.2cm (1.5in)
Min tank size: 100 litres
Difficulty level: Intermediate
Aquarium type: Community
Swimming level: All levels

Distribution and habitat

distribution map for Black line penguin tetra, Thayeria boehlkei

Origin: South America: upper Amazon River basin in Peru and Araguaia River in Brazil.

Habitat: Slow moving water in rivers and streams among vegetation


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Characiformes
Family: Characidae
Genus: Thayeria
Species: T. boehlkei Weitzman, 1957

Common name:
Black line penguin tetra

Synonyms: None