Phenacogrammus interruptus

Common Names: Congo tetra

Type Locality: Stanley Pool in the lower Congo River

Range: Congo River

Taxonomic Troubles: Originally described as Micralestes interruptus. Some taxonomists have returned to this name, so you may see it listed as either.

Size: 9 cm TL (3 1/2 inches).

Preferred Water Chemistry: Tropical; quite adaptable in terms of pH and hardness, soft and acid for spawning.

Difficulty: A dependable fish for intermediate and advanced hobbyists, but needs a large tank, as it is a large tetra that must be kept in schools. This species cannot tolerate poor water conditions, so frequent water changes are necessary.

Tank Setup: Open swimming space is necessary to show off this fish, with suitable hiding places along the back and sides. A planted tank is perfect. An excellent community fish with non-aggressive species of similar size, this fish can be timid and often requires s

Feeding: Omnivorous, should have some vegetable matter, but most of the diet should be meaty. Like most tetras, this fish particularly relishes live foods. Although large, they can lose out at meal time to more boisterous feeders. They may nibble on soft plants

Breeding: Congos are considered moderately difficult tetra to spawn. Condition the breeders with live foods, then provide warm, soft, acid water with plenty of plants or artificial spawning grass. The fry are large, but sensitive and a bit difficult to raise.


A robust tetra with beautiful finnage--extra long in the male, especially the dorsal fin and the extensions of the middle rays in the caudal. The colors are iridescent, primarily blue and bronze, with green and violet shimmering as the lighting changes.


This is the most popular of the African tetras. They are relatively expensive, so people often buy only a couple, but they are truly at ease only in large schools, and a dozen or two of these fish in a long tank makes a magnificent display. It is difficult to describe their beauty, or to capture it faithfully in a photo.

They’re active swimmers, and each twist and turn changes the angle of the light off the highly reflective scales, making the metallic colors kaleidoscope through the rainbow. As each fish moves independently, the effect with a large group is spectacular.

Another appeal is their elaborate finnage. The dorsal fin of a mature male may reach back to the tail. This is not a tetra for a 10- or 20-gallon community. THe longer the tank, the better. Their size, habits, and apparance make them ideal tankmates for rainbowfish, and many aquarists keep them successfully with the smaller, less vicious cichilds. As they swim in the upper regions of the water column, they will generally ignore and be ignored by any bottom-dwelling fishes. As with any long-finned fish, fin-nipping tankmates should be avoided.

Overall, this is an underappreciated species, even by many who keep it. Unless kept in a large school in a long planted tank, much of their beauty will be missed. It is well worth the investmenet!