Congo Tetra: Fish Species Profile

The Congo tetra is the African counterpart to the colorful tetras of South America. It shimmers with all the colors of the rainbow and uses this bright coloring for extravagant courtship displays by both males and females. Schools of these tetras look stunning in a tank, either on their own or with other peaceful fish species.

With an aquarium that offers sufficient space for swimming and interaction, these fish make great pets. Learn more about keeping Congo tetras as pets in your home aquarium.

Characteristics

Origin and Distribution

These African characin fish are found in the Congo River Basin. They inhabit streams, tributaries, pools, and marshes, preferring murky, slightly acidic water. The Congo tetra typically congregates in areas with tall vegetation, few trees, and substrates of sand, silt, and mud. Swimming in large schools, these tetras feed on worms, crustacea, insects, plant matter, and algae.

The Congo tetra (Phenacogrammus interruptus) was not discovered until 1949 and was not commonly imported as an aquarium fish until the 1960s. In the 1970s, Florida fish farmers perfected a breeding line, and most specimens in pet stores today descend from it. They breed true, showcasing the vibrant colors and beautifully trailing tails of their native African counterparts.

Colors and Markings

In the wild, the fish can grow up to 3 1/2 inches. However, farm-raised varieties, while richly colored and full-finned, typically do not exceed 3 inches. They have long, flat bodies with large scales.

This fish displays remarkable rainbow luminescence throughout its body. It is generally blue on top, red and gold in the middle, and blue on the belly. Males also feature long, flowing fins with violet and white edges, and their tail fins boast an elongated middle section.

Tankmates

Congo tetras are schooling fish that can become anxious if not part of a group of at least six of their species. When housed with fish of the same size or smaller, Congo tetras remain generally peaceful.

Ideal tankmates include:

• Other tetras, such as Neon and Cardinal tetras
• Rainbowfish
• Corydoras catfish
• Mollies
• Guppies
• Platies
• Harlequin rasbora
• Swordtails
• Celestial pearl danio
• Dwarf cichlids

Avoid aggressive species that will bully your Congo tetras. Do not keep Congo tetras with fin-nipping fish, such as tiger barbs, as the males' spectacular fins can be damaged.

Congo Tetra Habitat and Care

Since they need to be kept in schools, a 30-gallon aquarium is the minimum size required for six to eight Congo tetras. For large schools or when mixed with other species, consider using a 55-gallon aquarium. To maintain their health, provide ample space and meticulously filtered water. If water quality declines, Congo tetras might lose their coloration or develop damaged fins.

Congo tetras are hardy fish but only thrive in well-maintained habitats. They prefer still, dark, soft, peat-filtered water with low light levels, achievable with dim aquarium lights and floating plants. They favor darker substrates and enjoy nibbling on bottom-growing plants.

Congo Tetra Diet and Feeding

Congo tetras are omnivores, naturally feeding on insects, worms, plant matter, and algae. As pets, they are easy to feed and enjoy live, fresh, and flake foods, along with brine shrimp and bloodworms.

Feed these fish small amounts several times a day. If you don’t see your Congo tetras eating, don’t worry—they may be shy about feeding while being watched.

If your fish aren’t getting enough food, consider a behavioral feeding ring. This device floats on the water’s surface and keeps food together, making it easier for them to find.

Gender Differences

Males are more colorful than females, and they are also larger with more elaborate fins, characterized by a centrally extended caudal fin and a pronounced dorsal fin. Females are mostly golden with silver and green hues and lack the elaborate fins of males.

Breeding the Congo Tetra

A larger breeding tank is necessary for Congo tetras due to their size and their tendency to produce 300 or more eggs, most of which will likely hatch. The fry will grow quickly, reaching a size larger than full-grown neon tetras in four to five weeks.

Use a 15- or 20-gallon long tank for breeding; 10-gallon tanks are not recommended. Boil enough peat moss to cover the tank's bottom with 1 inch of loosely packed substrate (about a 1/2 cubic foot for a 20-gallon tank). Fill the tank with reverse osmosis, distilled, or rural rainwater, and allow it to sit for a few days until the peat moss settles, creating a soft, acidic water environment.

Position several thickets of Java moss atop the peat moss substrate in various locations. Include additional nylon breeding mops or clumps of fine-leaved plants. Maintain the water temperature at a steady 77°F. Avoid aeration or filtration to prevent disturbing the peat moss and clouding the water.

Introduce a well-conditioned pair of Congo tetras, previously kept in separate tanks, into the breeding tank shortly before lights out or sunset. Most pairs will spawn the next morning or when the lights are turned on. Maintain darkness for at least eight hours to stimulate spawning.

During spawning, the fish dive into the Java moss or spawning mops, releasing eggs and milt side by side. Some eggs stay in the plant or mop, but most fall into the peat moss substrate. Remove the breeders after spawning; the majority of eggs are not eaten as they are well hidden under the substrate.

Typically, 300 to 500 or more eggs are laid, with hatching occurring five to eight days after spawning. This contrasts with their South American relatives, whose eggs hatch more quickly, but whose fry initially hang on plants, being smaller and more helpless. Congo tetra fry emerge from the peat substrate fully free-swimming and hungry.

Congo tetra fry can be fed infusoria for a day or two before transitioning to baby brine shrimp. They grow quickly and begin accepting powdered dry food within two weeks, rapidly reaching nearly 1 inch. Within three months, frequent feedings of live and commercial growth foods will increase their size to 2 inches, at which point they begin to show color. While genders can be determined by then, they will be 6 months old and 3 inches long before they’re ready to breed. This rapid growth underscores the need for a larger tank.

Do not remove the peat from the fry rearing tank, as the fish need it for water quality. Placing them directly into freshwater can lead to fungal infections. Adult fish also benefit from peat moss in the filter or substrate to maintain slightly acidic water.

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:

• Buenos Aires tetra
• Red serpae tetra
• White skirt tetra

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