Congo Tetra Fish Breed Profile

Contgo Tetra Comunity Aquarium Fish
Thomas R. Reich PhD

The colorful tetras of South America have relatives that are just as colorful in the region of the Congo River in Africa. One of these species is the Congo Tetra, which shines in all the colors of the rainbow. It was not discovered until 1949 and was not imported as a common aquarium fish until the 1960s. For years, aquarists tried to breed this species successfully and had mixed results, as the beauty of the fish diminished with each successive breeding out of their native Congo River, with the extended central tail area all but disappearing in successive generations.

Then in the 1970s, Florida fish farms perfected a breeding line, and most examples of this species found in stores today descend from this strain. The Congo Tetras that you buy in most stores today will breed true, with all the color and trailing tail of the native African fish.


Scientific Name Phenacogrammus interruptus

Alestopetersius interruptus, Hemigrammalestes interruptus, Micralestes interruptus

Common Name Congo Tetra
Family Alestiidae
Origin Congo River, Zaire
Adult Size 3–3 ½ inches
Social Peaceful schooling fish
Lifespan 3–5 years
Tank Level All levels
Minimum Tank Size 40 gallons
Diet Omnivores
Breeding Egg layer
Care Moderate
pH 6.0–6.5
Hardness Prefer soft water
Temperature 73.0–82.0 degrees Fanhrenheit (22.8–27.8 degrees Celsius)

Origin and Distribution

These African Characins are found in the upper reaches of the River Congo in Zaire. They populate streams, tributaries, pools, and marshes, preferring murky, slightly acidic water. Congo Tetra generally congregates in areas with tall vegetation, few trees, and substrates made up of sand, silt, and mud. Swimming in large schools, the Tetra feed on worms, crustaceans, insects, plant matter, and algae.

Colorings and Markings

The fish in nature approaches 4 1/2 inches. However farm-raised varieties, though full finned and rich with color, will generally not grow beyond 3 or 3 1/2 inches. They have long, flat bodies with large scales; males also have long, flowing fins that are violet with white edging.

What makes these fish special is their amazing rainbow luminescence in their bodies from back to front, They are generally blue on top, red and gold in the middle, and blue on the belly.


Congo Tetras are schooling fish and can get nervous if they are not part of a group of at least six of the same species. If kept with other fish of the same size or larger, Congo Tetras are generally peaceful. Avoid aggressive species, as they will bully your Congo Tetras.

Congo Tetra Habitat

Congo Tetras are fairly hardy, but only if kept in habitats that are maintained correctly. They prefer still, dark, soft, peat-filtered water and low light levels. This can be achieved with dim aquarium lights and floating plants. They like darker substrates and enjoy nibbling on bottom-growing plants.

To help your pets maintain good health, you'll need to provide them with plenty of space (40 gallons is ideal) and carefully filtered water. If the quality of the water drops, Congo Tetras may lose some of their colorations or wind up with damaged fins.

Congo Tetra Diet

Congo Tetras are omnivores which, in the wild, eat insects, worms, plant matter, and algae. As pets, they are easy to feed: they enjoy live, fresh, and flake foods as well as brine shrimp and blood worms. They should be fed small amounts several times a day. Don't worry if you don't actually observe your Congo Tetras eating, as they can be shy about eating while being watched.

Sexual Differences

Males are much more colorful than females; they are considerably larger and have more elaborate fin structure. The females are mostly golden with shades of silver and greenish and have no exotic finnage.

Breeding the Congo Tetra

Breeding is really quite easy. First, you will need a larger breeding tank than for most tetras, because of the size of the breeders themselves, and because they will produce 300 or more eggs, which will most likely all hatch into fry. This fry will grow rapidly to a size larger than full-grown Neons in a month or five weeks.

Use a 15 or 20-gallon long tank for this project, and although a 10 gallon will work in a pinch, it is not recommended. Boil enough peat moss to cover the bottom of the tank with one inch of loosely packed moss substrate (about 1/2 cubic foot for a 20-gallon long tank). Put it in a tank filled with reverse osmosis, distilled, or rainwater if in a rural area, and let it sit for five days until the peat moss has completely settled evenly on the bottom of the tank.

Place several thickets of Java moss on top of the peat moss substrate in several strategic locations. Also, provide several nylon breeding mops or several clumps of fine-leaved plants. The water temperature should be a steady 77 F. There should be no aeration or filtration since this would disturb the peat moss and cloud the water.

Place a well-conditioned pair of Congo Tetra, which has been kept in separate quarters into the breeding tank shortly before turning out the lights, or shortly before sunset. Most pairs will spawn the following morning, or when the lights are turned back on at least eight hours later. The male instigates courtship by chasing the female up and down the aquarium and flaring his fins at her. At this time his colors are absolutely stunning.

Once the female is fully aroused, begin diving into the Java moss or spawning nylon mop as they start to shudder side by side. At this time they release eggs and milt. Some of the eggs remain in the plant or mop, but most fall into the peat moss substrate. As the breeding activities continue, the peat moss will be stirred up, and the water may become quite cloudy. Don’t worry as it does not hamper the breeding. When they are finished, you may take your time, but remove the breeders to separate reconditioning quarters. The eggs will not be eaten since most are well hidden under the peat moss substrate.

Usually, 300 to 500 or more eggs are laid and hatching occurs from five days onward. It may take a week for some of the eggs, so be patient. This differs sharply from their South American relatives, whose eggs hatch much quicker, but whose fry hang on the sides or on plants for several days and are smaller and helpless at first. When the fry appears from the substrate, they are fully free swimming and hungry.

Congo Tetra fry can be fed infusoria for a day or two before they will take baby brine shrimp. They will grow quickly and take powdered dry food within two weeks, soon reaching almost an inch long. Within three months of frequent feedings of live and commercial growth foods, they will reach two inches and show signs of color. At this point, it is even possible to determine sex, but it will be six months and nearer to three inches before they are sexually mature. With growth this quick, the need for a larger tank is obvious.

It is very important not to remove the peat from the fry rearing tank. The fish need it for water quality, and if you put them in freshwater, they are liable to succumb to fungus. The adult fish also prefer peat moss in the filter or substrate, but it is not necessary and tends to brown the water, so it is not really recommended.

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