Congo tetra

Phenacogrammus interruptus

Iridescent scales and extended fins in mature males

Juveniles may look subdued. Mature males develop conspicuous iridescence and extended fins. A group needs a longer swimming run than many small tetras.

Adult length: Up to 8 cm (standard length, without the tail fin)
Water temperature: 23–28 °C
pH: 6–7.5
Hardness: 3–18 dGH

Natural habitat: Native to the lower and middle Congo basin in the Republic of the Congo and Democratic Republic of the Congo.

Plan for an adult group in a long aquarium. Avoid fin nippers and domineering companions.

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Appearance and identification

Look at the body shape, large iridescent scales and the mature male's extended dorsal and caudal fins. Females look different.

Same-species behaviour

Keep a group of its own species with a mix of sexes.

Space requirements

A 120 × 30 cm footprint for adults. Keep a continuous swimming lane even when the sides are densely planted.

Diet and feeding

Offer appropriately sized dry foods with small live or frozen foods for variety.

Compatibility limits

Its adult size and active swimming may unsettle smaller, timid fish, while boisterous companions may frighten the Congo tetras. Consider both when selecting tankmates.

Aquarium environment

Plants and wood provide shelter, but leave open swimming space. Stable water quality matters to condition and fin health.

Sources

www.fishbase.se ↗ 2026-10-25

www.seriouslyfish.com ↗ 2026-10-21

researcharchive.calacademy.org ↗ 2026-10-22