Congo Tetra Fish Species Profile

Characteristics, Origin, and Helpful Information for Hobbyists

Contgo Tetra Comunity Aquarium Fish
Thomas R. Reich PhD

The colorful tetras of South America have Old World relatives in the region of the Congo River in Africa. These African counterparts are equally colorful. One of these species is the Congo tetra, which shimmers in all the colors of the rainbow. This loud coloring is used for extravagant courtship displays toward both the male and female.

Characteristics

Family Alestiidae
Origin Congo River, Zaire
Adult Size 3 to 3 ½ inches
Social Peaceful schooling fish
Lifespan 3 to 5 years
Tank Level All levels
Minimum Tank Size 40 gallons
Diet Omnivores
Breeding Egg layer
Care Moderate
pH 6.0 to 6.5
Hardness 3 to 18 dGH
Temperature 73.0 to 82.0 F (22.8 to 27.8 C)

Origin and Distribution

These African characin fish are found in the upper reaches of the River Congo in Zaire. They populate streams, tributaries, pools, and marshes, preferring murky, slightly acidic water. The 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.

This species was not discovered until 1949 and was not imported as a common aquarium fish until the 1960s. During the 1970s, Florida fish farms perfected a breeding line, and most specimens found in pet stores descend from this line. They will breed true, having all of the color and beautifully trailing tails of the native African fish.

Colors 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. This fish shows amazing rainbow luminescence along the whole body from back to front. They are generally blue on top, red and gold in the middle, and blue on the belly. Males also have long, flowing fins that are violet with white edging; the mail's tail fin is long and flowing along the vertical medial line.

Tankmates

Congo tetras are schooling fish that can get anxious 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 smaller, Congo tetras are generally peaceful. Ideal tankmates include other tetras, rainbowfish, and Corydoras catfish.

Avoid aggressive species, as they will bully your Congo tetras. Do not keep Congo tetras with any fin-nipping fish as the spectacular fins of the males will be destroyed.

Congo Tetra Habitat and Care

Congo tetras are fairly hardy, but only if kept in habitats that are maintained correctly. They prefer still, dark, soft, peat-filtered water with 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 fish maintain good health, you'll need to provide them with plenty of space 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 and Feeding

Congo tetras are omnivores; in the wild, they 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 observe your Congo tetras coming to the food, as they can be shy about partaking while being watched. If fish are not getting enough food, try a behavioral feeding ring.

Gender Differences

Males are much more colorful than females; they are considerably larger and have more elaborate fin structure with a centrally extended caudal fin and a large and pronounced dorsal fin. The females are mostly golden with shades of silver and greenish. Females have no such fanciful fins.

Breeding the Congo Tetra

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; all are most likely to hatch. Fry will grow rapidly to a size larger than full-grown neon tetras in four or five weeks.

Use a 15- or 20-gallon long tank for your breeding project; 10 gallons are 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). Add it to a tank already filled with reverse osmosis, distilled, or rainwater if in a rural area, and let it sit for a few days until the peat moss has completely settled.

Place several thickets of Java moss on top of the peat moss substrate in several locations. Provide additional nylon breeding mops or several clumps of fine-leaved plants. The water temperature should be a steady 77 degrees Fahrenheit. 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 lights out or shortly before sunset. Most pairs will spawn the following morning, or when the lights are turned back on; dark should be maintained for at least eight hours.

Spawning fish proceed to dive into the Java moss or spawning mops. During these dives, they release eggs and milt side by side. Some of the eggs remain in the plant or mop, but most fall into the peat moss substrate. Remove the breeders although most eggs will not be eaten since they are well hidden under the peat moss substrate.

Usually, 300 to 500 or more eggs are laid and hatching occurs from five to eight days after spawning. This differs sharply from their South American relatives, whose eggs hatch much quicker, but whose fry hang on plants for several days, being smaller and more helpless at first. When Congo tetra fry appear from the peat 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 in length. 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 possible to determine sex, but they will be six months old and three inches long before they are able to breed. With this quick growth, 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 straight into freshwater, they are liable to succumb to fungus. The adult fish also prefer peat moss in the filter or substrate.

More Pet Fish Species and Further Research

If these African Congo tetras appeal to you, but you are interested in some compatible South American fish for the same aquarium, read up on:

Check out additional fish species profiles for more information on other freshwater fish.

Article Sources
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  1. Congo Tetra (Phenacogrammus Interruptus) - Species ProfileNonindigenous Aquatic Species.Er.United States Geological Survey.Gov, 2020