Congo Tetra

Family: Alestiidae Congo Tetra, Phenacogrammus interruptusPhenacogrammus interruptusPhoto © Animal-World: Courtesy Ken Childs
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I've got 19 of these beauties in a 100gal in an african biotope tank with other congo basin species of fish, mixed sex group, the males look stunning. All the males... (more)  Ted22

The Congo Tetra has opalescent scales that shine in all the colors of the rainbow!

The Congo Tetra Phenacogrammus interruptusis a timid but incredibly beautiful fish. The most gorgeous of the true African Characins, its body has luminescent rainbow colors. This tetra's dorsal, anal, and tail fin develop into the most beautiful feathery appendages.

The males of this peaceful schooling fish can reach up to over 3 inches (8.5 cm) in length, so a group of these good-sized fish need a large aquarium. This fish needs plenty of room to swim around as well as to thrive and develop its full beauty.

The Congo Tetra prefers soft, peat filtered water and a dark 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 show off best in lower light levels, too. However, they sometimes do like to nibble on softer plants and young shoots.

They are generally a good community fish with other peaceful, similar sized companions, but they may try to bite smaller fish. These fish are easily frightened by aggressive tankmates and loud noises. Do not tap on the glass! They 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

Geographic Distribution
Phenacogrammus interruptus
Data provided by
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Characiformes
  • Family: Alestiidae
  • Genus: Phenacogrammus
  • Species: interruptus
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Congo Tetra - Quick Aquarium Care
  • Aquarist Experience Level: Intermediate
  • Size of fish - inches: 3.4 inches (8.51 cm)
  • Minimum Tank Size: 40 gal (151 L)
  • Temperament: Peaceful
  • Aquarium Hardiness: Moderately hardy
  • Temperature: 73.0 to 82.0° F (22.8 to 27.8° C)
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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) because it has a large population and no major widespread threats. They are found in Africa in the Zaire River region of the upper Congo Basin.

They are found in streams, tributaries, pools, and marshes with slightly acidic and murky waters. These habitats have tall vegetation around the margins and sandy bottoms, or in slow-moving pools the substrate can be thickly layered with silt and mud. There are few rocks in these areas and no branches or wood. The Congo Tetras swim in schools and feed on worms, crustaceans, insects, plant matter, algae, and other zooplankton.

  • 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. Males will reach about 3 1/3 inches (8.5 cm) in length, and females will reach about 2 1/3 inches (6 cm). They have a lifespan of between 3 to 5 years in the home aquarium.

Congo Tetra, Phenacogrammus interruptus
Photo © Animal-World

When mature, the fluorescent colors of the Congo Tetra run through the fish from front to back, starting with blue on top and 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) while females reach up to 2.75 inches (6 cm).
  • Lifespan: 5 years - They have a lifespan of about 3 to 5 years in the aquarium.

Fish Keeping Difficulty

The Congo Tetra is moderately hardy and suggested for fish keepers with some experience. Be careful picking tankmates as this peaceful, long-finned tetra is often a target for attacks by aggressive tankmates. These attacks can stress it out and the injuries can lead to diseases and death.

  • Aquarium Hardiness: Moderately hardy
  • Aquarist Experience Level: Intermediate

Foods and Feeding

The Congo Tetras are omnivorous. In the wild these fish are insectivores, feeding primarily on insects, but also eat small worms, crustaceans, plant matter, algae, and other zooplankton. In the aquarium 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 every day. Feed brine shrimp (either live or frozen) or blood worms as a treat. Feed them 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 they 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

Aquarium Care

Congo Tetras are not exceptionally difficult to care for provided their water is kept clean. Aquariums are closed systems and regardless of size, all need some maintenance. Over time, decomposing organic matter, nitrates, and phosphate build up and 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 to 50% of the tank water should be replaced every other week.

  • Water Changes: Bi-weekly

Aquarium Setup

The Congo Tetra has been successfully kept and even bred in aquariums as small as 20 gallons. This fish is commercially bred in huge numbers, so it is adaptable and will thrive in most well-maintained tanks. However, because they really need to be kept in schools of at least 6 fish, an aquarium of at least 40 gallons or larger is recommended. Water should be on the acidic side and soft with good circulation. Dim lighting will develop the tetra's best coloring.

To get the best out of this fish, set up a biotype tank. These fish prefer some plant cover and a dark gravel.  The Congo Tetra looks particularly effective in a heavily-planted setup and can appear a little washed out if 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 the leaves every few weeks.  

  • Minimum Tank Size: 40 gal (151 L) - This fish should be kept in groups of at least 6 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 setup will bring out this tetra's best coloration.
  • 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.

Social Behaviors

The Congo Tetra has a very timid temperament and should be kept in a school with at least 6 individuals of its own kind. They are generally a good community fish, but they may try to bite smaller fish. Also, they sometimes like to nibble on softer plants and young shoots.

This shy fish should not be housed with any of the more aggressive fish. The best tankmates are other tetras, rainbowfish, Corydoras, Loricariids, Synodontis, and some peaceful Cichlids. Do not keep Congo Tetras with fish that are known to be fin nippers as male Congos will sustain injuries.

  • Venomous: No
  • Temperament: Peaceful
  • Compatible with:
    • Same species - conspecifics: Yes
    • Peaceful fish (): Safe - This fish has a very timid temperament 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 (): Monitor - Tetras can out compete them for food.
    • Shrimps, Crabs, Snails: Safe - not aggressive
    • Plants: Monitor - They may snack on soft plant matter and new shoots.

Sex: Sexual differences

The male is larger and more colorful, and the tail fin and dorsal fin are more extended. In the picture above, you can see the extension at the center of the tail fin. A mature female will be more rounded.

Breeding / Reproduction

The Congo Tetras are egg layers and have been bred in captivity. They are bred commercially for the aquarium trade, however, breeding these fish in home aquariums can be a bit of a challenge. Getting a pair to spawn is moderately difficult.

To breed them, 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 parents should be removed after spawning so they don't eat the eggs. The newly hatched 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 shallower water.

Fish Diseases

The Congo Tetras are fairly hardy and disease is not usually a problem in a well-maintained aquarium. However, they are prone to developing ich if kept in colder temperatures. Also, remember that anything you add to your tank can introduce 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 as 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 dealt with 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 a well-balanced diet. The more closely their environment resembles their natural habitat, the less stress the fish will have, making them healthier and happier. A stressed fish is more likely to acquire disease.

As with most fish, 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 more expensive than many tetras.


Author: Clarice Brough CFS, David Brough CFS, Jeremy Roche
Lastest Animal Stories on Congo Tetra

Ted22 - 2012-02-22
I've got 19 of these beauties in a 100gal in an african biotope tank with other congo basin species of fish, mixed sex group, the males look stunning. All the males are around 4 inches and what I thought was fully grown. Looked in the local fish shop today and they had large congos for sale. a good 5 inches + they dwarfed my fish. The person who said they grow this big was talking complete sense, nothing documented online for congo tetras of this size but they do exsist and presumably all have the potential to grow to this size (unless they were hormone treated or something). Fantastic fish, definately more rowdy than this article makes them out to be, voracious feeders they swarm and tear food apart like a group of beautiful pirahnas, all my fish are large semi aggro and the congos hold thier own wonderfully! Just another thing, I wouldnt keep a group of these in anything less than a 4 ft tank, they certainly like their swimming space!

hisham - 2010-09-09
Can albino congo tetras live with discus?

  • Anonymous - 2010-09-20
    I wouldnt put the two of them in the same tank because of the different temperatures they do best in.
MIke C - 2004-11-28
These Fish are amazing, the colouration of them is usually not seen while at the store, but once they grow up a bit they glow (more obvious when not looked at straight on).

They can reach a max length of 5" tho, so make sure you have a larger tank for these fish. I have 4 in a 75Gal and they play well, tho they are agressive when fed (will knock other fish out of the way for food)

  • Alex Burleson - 2012-01-09
    They are certainly a beautiful, and exciting specimen for most community aquariums!
Mike - 2010-02-27
Beautiful fish. I have 7 in a 30 gallon in addition to some other fish.

Someone here said they reach a max of 5 inches, but everything everywhere I've read said that males get to 3.5 inches, and females stay closer to 2.5 inches.

they seem to get along well in a community tank.

Plus, you have the joy of having very rare tetras which 90% of other people don't have.

I take pride in having rare fish. And the Congo's fit right in with my African Butterfly, Leopard Ctenopoma, Female Krib, and cories.

  • cheryl - 2010-09-04
    I have some of these & am going to expand the school as a larger fish in the tank died. They are beautiful & mine are not timid at all. I have the ones that look more olive green/electric blue & I am having a hard time finding more of those. Mine are getting along nicely with African Red Eyed Tetras (another less known, awesome fish! - not to be confused with Red Eye Tetras) a Giant Danio that has a blue-green sheen to him, a large killifish (that I believe was mislabeled as a gardneri) & a couple of peppered cory cats. I have a blue-green iridescent thing going on somehow... I have a Leopard Ctenopoma that i would be afraid to put with these because he is (& so has every other one I've owned) a little on the aggressive side. They like to chase other fish, especially when the lights are out. They are one of my favorite fish.