Congo Tetra Care: Mimicking the Congo River

Congo tetra (lat. Phenacogrammus interruptus) is a timid, but unspeakably beautiful aquarium fish. Probably, it is the most gorgeous fish of the Alestidae family. A tank, which has tetra fishes in it, should be thickly planted. The majority of these fishes has a very good looking coloring (due to some special pigments they have, that change their color under different kinds of lights).

Habitat in the wild

Congo tetra (Phenacogrammus interruptus) was described in 1899. Congo Tetras are native to the Democratic Republic of the Congo – Zaire river basin, Congo river upstream.

Within their natural habitat, Congo Tetras typically inhabit slow-moving rivers, streams, and flooded forest areas. These water bodies are often characterized by dense vegetation, submerged branches, and leaf litter. The fish can be found in both clear and turbid waters, and they prefer areas with moderate water flow.

Congo Tetras are known to occupy different levels of the water column, from the midwater to the upper regions. They are adapted to the dimly lit environments found under the forest canopy, where sunlight is filtered through the vegetation.

In their natural habitat, Congo Tetras coexist with a variety of other fish species, including other tetras, characins, cichlids, and catfish. It’s a schooling fish that forming groups or schools to provide safety and social interaction.



How big do congo tetras get?

Is rather large fish for tetra kind – congo tetra male typically reach a maximum size of around 3.5 to 4 inches (9-10 cm) in length and the female – up to 6 cm correspondingly. However, it’s important to note that individual sizes can vary slightly, with males often being larger than females.


How long do congo tetras live?

Congo Tetras have an average lifespan of about 3 to 5 years under proper care and conditions.


Congo Tetras have a streamlined and elongated body shape, typical of most tetra species.

The congo tetra has lush fins – the ones of the male have long veiled edges (on dorsal, fluke and anal fins). The fins of Congo Tetras are well-developed and add to their elegance. They have a prominent dorsal fin that extends from the middle of their body to the tail. The anal fin and caudal fin (tail fin) also contribute to their overall appearance. Male has three-bladed tail with a pronounced middle blade.


The body coloring is opalescent – the colors vary from tints of blue on its back to red-orange and gold yellow on the sides and again there are bluish colors on the abdomen.

Scientific NamePhenacogrammus interruptus
Common NameCongo Tetra
Adult SizeUp to 3.5 to 4 inches (9-10 cm)
Lifespan3-5 years (can vary based on care and conditions)
Water ParameterspH: 6.0-7.5
Temperature: 75-82°F (24-28°C)
Hardness: Moderate
Tank SizeMinimum 20 gallons for a small group, larger for larger groups
BehaviorPeaceful, shoaling fish
CompatibilityPeaceful community fish, tetras, rasboras, dwarf cichlids
DietOmnivorous, accepts flakes, pellets, live/frozen foods
Natural HabitatSlow-moving rivers, streams, and flooded forest areas
Preferred Water FlowModerate
Preferred LightingDim lighting with some shaded areas
ColorationIridescent blue upper body, bright red/orange/yellow fins
Breeding DifficultyModerate
Breeding TriggerTemperature drop, increased water flow, soft water conditions
Social StructureShoaling fish, thrives in groups of 6 or more
Suitable Tank SetupWell-planted tank with open swimming space

Care and keeping in a tank

Due to the fact that fish can jump out of the water, the tank should be tightly closed. The fish school prefers swimming in upper and middle layers of water.

Tank size

Since this congo tetra is quite large for tetra kind and it’s a schooling one, you may need a minimum tank size of 20 gallons (75 liters) is often suggested for a small group of Congo Tetras. However, keep in mind that larger tanks are generally better for these active and shoaling fish. The tank should have dimensions that allow for horizontal swimming space, as well as some vertical space for the fish to explore.

Water parameters

In their habitat the fish lives in soft and acidic water. Congo Tetras prefer moderate water hardness. Aim for a general hardness (GH) level of 5-12 dGH (German degrees of hardness) and a carbonate hardness (KH) level of 2-8 dKH. Aim for a slightly acidic to neutral pH range of 6.0-7.5. Congo Tetras can tolerate a slightly broader pH range, but maintaining it within this range is ideal.

Keep the water temperature in the range of 75-82°F (24-28°C). This range reflects the tropical environment they are native to and promotes their overall health and activity.

When putting the congo tetra into a new tank you should use some substances for artificial water aging, some peat substances or put a peat stuffing into a filter. Also you may use the water from the tank you’ve already had.

As for care – since the fish won’t do with large amount of fresh water, the renews should be made every month and be equal to 1/5-1/6 of the tank capacity, but this works only in case if there are no other fishes in the tank. If you have some other fishes in the tank, then increase the water renew gradually up to weekly renew of 20% of tank capacity. Water aeration and filtration are also required in the tank.

Tank decor

The fishes look good in a school. To create the space in a tank so, that the whole school is seen and not hidden among the tank plants, it’s necessary to put them thickly almost without any space between the plants. Therefore, some free space is left around the front tank wall and there the school can swim.

Ideally it’s better to create a native biotope – dark tank substrate, lots of plants, some snags. Use driftwood or branches to simulate the submerged wood and branches found in their natural habitat. These additions offer hiding spots and create interesting swimming areas. You can put some plant leaves on the bottom to make the tank water brownish as the habitat – River Congo has. Use a fine-grained substrate like sand or small-sized gravel to resemble the sandy or muddy river bottoms where Congo Tetras are found. Avoid sharp or rough substrates that could damage their delicate fins.

Consider using subdued or dim lighting to replicate the natural lighting conditions found under the forest canopy. This can help create a more comfortable and calming environment for Congo Tetras.


Congo Tetras (Phenacogrammus interruptus) are omnivorous fish that require a balanced diet to thrive. A good-quality staple flake or pellet food formulated for tropical fish can serve as the foundation of their diet. Tetras greatly benefit from occasional feedings of live or frozen foods to mimic their natural diet. Offer them treats like brine shrimp, daphnia, bloodworms, and mosquito larvae. Th

The congo tetra should have a plant in diet. It should consist of 60% of animal feed (blood worm, tubifex, brine shrimp) and 40% of plant feed (filamentous alga, spinach, feeds containing spirulina). Otherwise, if the fish diet has lack of plant components, congo tetra may start eating soft parts of tank plants. You can supplement their diet with blanched spinach, lettuce, or finely chopped vegetables like zucchini or cucumber.

One of possible troubles that may arise – since the fish is a rather timid one, it may not be able to compete with more active tank mates for feed or it even won’t eat the feed till you are around.

Tank mates

Congo Tetras (Phenacogrammus interruptus) are generally peaceful and can coexist with a variety of compatible tank mates. Tank mates can consist of the majority of small african and South American fishes, live-bearing fishes and barb (except, maybe the tiger barb), corydoras (like pygmy or panda), dwarf cichlids like ram cichlid. However, still it’s more proper to keep congo tetras in a school of 4-20 species separately from other fishes.

Here are some suitable tank mates for Congo Tetras:

Gender differences: male vs female

Congo tetra male may have a more elongated body shape and grow to be a bit larger in length. Male often display more elongated and flowing fins compared to females. The dorsal fin, in particular, is usually more pronounced and can extend farther back along their body. Males also tend to have more intense and deeper coloration, especially during courtship or when displaying to assert dominance. The female is small, significantly less bright colored and their abdomen is larger and more rounded. Females may have a slightly rounder belly shape, particularly when they are carrying eggs. This is more noticeable when they are in breeding condition. In general, it’s rather easy to see between the adult fishes of this kind.


Approximately 2 weeks earlier before breeding starts the congo tetra male and female should be put apart into different tanks and fed well and high. The fish becomes reproductive at the age of 8-9 month.

The spawning may occur both within a couple and in a school, but the latter is more desirable (the males should prevail in this case). A spawning tank should be of 20 liters of 100-150 liters capacity correspondingly.

The spawning is seasonal and usually the morning one. It’s activated by adding of fresh, soft water; temperature and water flow increase; light day extension and high feed. The eggs are shed among the plants or on the tank bottom. Please, note, that in the old water, due to high content of nitrogen compounds in it, the juveniles stop growing and die as a rule.

Put a separating grid on the spawning tank bottom and it’s desirable to put a large bush of Thai fern on top of it. Water hardness is 1,5-5, pH 6,8-6,5, water temperature 25-28 °C.

After pouring water into the spawning tank, close it with clean glass and give the water about 2 weeks to settle. But don’t forget that the water settles using aeration. Put congo tetras into the spawning tank in the evening. Gradually raise the water temperature up to the optimal value. As a rule, the spawning stars in 2-6 days and it lasts for about 2.5 hours.

The light should be bright and close to the sunlight. The fish productivity is 300-500 transparent not sticky eggs. After the spawning remove the fishes, the substrate and the grid from the spawning tank and replace almost all tank water with the water with the same parameters and color it with methylene-blue a little.

The eggs should be shaded and the whitened ones should be removed. The healthy eggs are round and completely transparent.

The eggs incubation time is 5-7 days. One or two days earlier before larva appear decrease the tank water level up to 3-5 cm. The juveniles hatch in 6-7 days and they start swimming and feeding right away.

Start feed for congo tetra juveniles is infusorians, rotifers, boiled egg yolk, starting from the second week of juveniles life they can be fed with brine shrimp nauplii and cyclops, Vinegar eels.