Congo Tetra
Family: Alestiidae
Phenacogrammus interruptusPhoto © Animal-World: Courtesy Ken ChildsThe Congo Tetra has opalescent scales that shine in all the colors of the rainbow!
The Congo Tetra Phenacogrammus interruptus is timid, but an incredibly beautiful fish. It is the most gorgeous of the true African Characins. Its body has luminescent rainbow colors and its dorsal, anal, and tail fin develop into the most beautiful feathery appendages.
This is a peaceful schooling fish with males that can reach up to over 3 inches (8.5 cm) in length. A group of these good sized fish need a large aquarium, not only to provide plenty of room to swim around, but to thrive and develop their full beauty as well.
The Congo Tetra prefers soft, peat filtered water and a darker substrate. They are most comfortable in an aquarium with lower light levels which can be provided by floating plants. The beautiful rainbow colors of this fish will also show off best in lower light levels. These fish are easily frightened by aggressive tank mates and loud noises. Do not tap on the glass! These fish are also timid eaters and may wait for you to leave the aquarium before they will feed.
For Information on keeping freshwater fish, see:
Freshwater Aquarium Guide: Aquarium Setup and Care
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- Temperament: Peaceful
- Aquarium Hardiness: Moderately hardy
- Aquarist Experience Level: Intermediate
- Diet Type: Omnivore
- Minimum Tank Size: 40 gal (151 L)
- Temperature: 73.0 to 82.0° F (22.8 to 27.8° C)
- Range ph: 6.0-7.5
- Hardness Range: 4 - 18 dGH
- My Aquarium - Enter your aquarium to see if this fish is compatible!
- Beginner Fish - Freshwater fish for beginners
- Community Fish - Peaceful Freshwater fish
- Hardy Fish - Hardy Freshwater fish
- Similar size fish - Fish that are 1 inch bigger or smaller
- Coldwater Fish - Looking for cold water fish? (65 °)
Habitat: Distribution / Background
The Congo Tetra Phenacogrammus interruptus was described by Boulenger in 1899. This species is listed on the IUCN Red List as Least Concern (LC) as it has a wide population and no major widespread threats. They are found in Africa, in the Zaire River region of the upper Congo Basin which is slightly acidic and murky waters. They swim in schools and feed on worms, crustaceans, insects and plant matter.
- Scientific Name: Phenacogrammus interruptus
- Social Grouping: Groups
- IUCN Red List: LC - Least Concern
The Congo Tetra has a full-bodied typical tetra shape with rather large scales. The male will reach about 3 1/3 inches (8.5 cm) in length and the female will reach about 2 1/3 inches (6 cm). They have a lifespan of between 3 to 5 years in the home aquarium.
When mature, the fluorescent colors of the Congo Tetra run through the fish from front to back starting with blue on top changing to red through the middle, to yellow-gold, and back to blue just above the belly. The fins are grayish violet with white edges.
- Size of fish - inches: 3.4 inches (8.51 cm) - The males get up to 3.5 inches (8.9 cm). Females up to 2.75 inches (6 cm).
- Lifespan: 5 years - They have a life span of about 3 - 5 years in the aquarium.
The Congo Tetra is moderately hardy and suggested for a fish keeper with some experience. Be careful picking tankmates as this peaceful long finned tetra is often a target of attacks which can stress it out and the injuries can lead to diseases and death.
- Aquarium Hardiness: Moderately hardy
- Aquarist Experience Level: Intermediate
In the wild the Congo Tetra feeds primarily on insects, but also eats worms, crustaceans, insects and plant matter. Since they are omnivorous the Congo Tetra will generally eat all kinds of live, fresh, and flake foods. To keep a good balance give them a high quality flake food everyday. Feed brine shrimp (either live or frozen) or blood worms as a treat. It is best to feed several times a day and only what they can consume in 3 minutes or less at each feeding.
- Diet Type: Omnivore - In the wild these fish are primarily insectivores but can usually be trained to take live foods, large flakes, and pelleted foods.
- Flake Food: Yes - Provide large flakes.
- Tablet Pellet: Yes
- Live foods (fishes, shrimps, worms): Some of Diet
- Vegetable Food: Some of Diet
- Meaty Food: Some of Diet
- Feeding Frequency: Several feedings per day
Congo Tetras are not exceptionally difficult to care for provided their water is kept clean. Aquariums are closed systems and regardless on size all need some maintenance. Over time decomposing organic matter, nitrates, and phosphate build up and the water hardness increases due to evaporation. To combat these ever changing conditions water should be replaced on a regular basis, especially if the tank is densely stocked. At least 25 - 50% of the tank water should be replaced every other week.
- Water Changes: Bi-weekly
The Congo Tetra has been successfully kept and even bred in aquariums as small as 20 gallons. It’s commercially bred in huge numbers so it is adaptable and will thrive in most well-maintained tanks. But because they really need to be kept in schools of at least six fish, an aquarium that is at least 40 gallons or larger is recommended. Water should be on the acidic side of neutral and soft with good circulation. Using dim lighting will develop the tetras best coloring.
To get the best out of this fish, set up a biotype tank. These fish prefer some plant cover and a darker gravel. It does look particularly effective in a heavily-planted setup and can appear a little washed out the decor is too sparse. For the substrate use a river sand with some drift wood and twisted roots. Add some dried leaves to the tank, which will stain the water a light brown, and then replace leaves every few weeks.
- Minimum Tank Size: 40 gal (151 L) - This fish should be kept in groups of at least six and requires plenty of swimming space.
- Suitable for Nano Tank: Sometimes
- Substrate Type: Any
- Lighting Needs: Low - subdued lighting - Low lighting and a shadowy tank set up will bring out the best coloration on this fish.
- Temperature: 73.0 to 82.0° F (22.8 to 27.8° C)
- Range ph: 6.0-7.5
- Hardness Range: 4 - 18 dGH
- Brackish: No
- Water Movement: Moderate
- Water Region: All - These fish will swim in all areas of the aquarium.
They are generally a good community fish but they may try to bite smaller fish. Also, watch that they don't eat your smaller plants. They sometimes like to nibble on softer plants and young shoots. Best tank mates for this fish are other tetras, rainbowfish, Corydoras, Loricariids, Synodontis, and some peaceful Cichlids. Do not keep Congo Tetras with fish that are known to nip fins as male Congo's will be injuried.
- Venomous: No
- Temperament: Peaceful
- Compatible with:
- Same species - conspecifics: Yes
- Peaceful fish (): Safe - This fish has a very timid temprament and should not be housed with aggressive or fin nipping fish.
- Semi-Aggressive (): Threat
- Aggressive (): Threat
- Large Semi-Aggressive (): Threat
- Large Aggressive, Predatory (): Threat
- Slow Swimmers & Eaters (): Safe
- Shrimps, Crabs, Snails: Safe - not aggressive
- Plants: Monitor - They may snack on soft plant matter and new shoots.
The male is larger with more color, also the tail fin and dorsal fin are more extended. If you look at the picture above, you can see the extension at the center of the tail fin. A mature female will be more rounded.
![]() Photo © Animal-World |
The Congo Tetras are egg layers. Some keys to breeding them is to provide a large aquarium with peat filtered water and bright lighting to initiate spawning. They will lay up to 300 eggs that will drop to the bottom. The fry are large enough to eat freshly hatched brine shrimp. For a description of breeding characin fish, see Breeding Freshwater Fish: Characins.
- Ease of Breeding: Moderate - Getting a pair to spawn is moderately difficult. The morning sun will initiate a pair to spawn in more shallow water. The parents should be removed after spawning.
The Congo Tetras are fairly hardy and disease is not usually a problem in a well maintained aquarium. However they are prone to developing ick if kept in colder temperatures. Also anything you add to your tank can bring disease. Not only other fish but plants, substrate, and decorations can harbor bacteria. Take great care and make sure to properly clean or quarantine anything that you add to an established tank so not to upset the balance.
A good thing about Congo Tetra is that due to their resilience, an outbreak of disease can often be limited to just one or a few fishes if you deal with it at an early stage. When keeping more sensitive types of fish, it is common for all fishes to be infected even before the first warning signs can be noticed. The best way to proactively prevent disease is to give your fish the proper environment and give them a well balanced diet. The closer to their natural habitat the less stress the fish will have, making them healthier and happy. A stressed fish is more likely to acquire disease.
As with most fish the Congo Tetras are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial disease. It is recommended to read up on the common tank diseases. Knowing the signs and catching and treating them early makes a huge difference. For information about freshwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.
The Congo Tetra is readily available but is more expensive than many tetras.
- Animal-World References: Freshwater Fish and Plants
- Dr. Rüdiger Riehl and Hans A. Baensch, Aquarium Atlas Vol. 1, Publisher Hans A. Baensch, 1991
- Glen S. Axelrod, Brian M. Scott, Neal Pronek, Encyclopedia Of Exotic Tropical Fishes For Freshwater Aquariums, TFH Publications, 2005
- Joseph S. Nelson, Fishes of the World, Wiley, 2006.
- Marc Ladonne, Aquarium Fish , Barnes Noble, 1999
- Dr. Herbert R. Axelrod, Aquarium Fishes of the World, TFH Publications, 1998
- Dr. Herbert R. Axelrod, Dr. Warren E Burgess, Dr. Cliff W. Emmens, Neal Pronek, Jerry G. Walls, Ray Hunziker, Dr. Axelrod's Mini-Atlas of Aquarium Fishes, Mini- Edition, T.F.H. Publications, Inc., 1987
- Phenacogrammus interruptus (Boulenger, 1899) Congo tetra, Fishbase.org
- Phenacogrammus interruptus, The IUCN Red List of Threatened Species
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