Phenacogrammus interruptus (Congo Tetra)

26 June 2026

521

Hailing from the Congo River basin, the Congo Tetra is a stunning, iridescent schooling fish prized for its flowing fins and rainbow hues. Though slightly larger than typical tetras, their peaceful nature and active swimming make them a highly popular centerpiece for planted community aquariums.

Phenacogrammus interruptus (Congo Tetra)

Overview

The Congo Tetra (Phenacogrammus interruptus) is widely regarded as one of the most magnificent freshwater fish available in the aquarium hobby. Unlike many of the smaller South American tetras, this African species boasts a larger, more robust profile, complemented by spectacular iridescent coloration and beautifully elongated finnage in mature males. They are an excellent choice for aquarists looking to add a vibrant, active school of fish to a medium-to-large planted community tank.

Image of congo tetra med phenacogrammus interruptus

Distribution and Habitat

Endemic to the central Congo River basin in Africa, these fish are primarily found in the Democratic Republic of the Congo. They inhabit the murky, slightly acidic, and heavily vegetated streams, tributaries, and pools of the region. The natural waters they swim in are typically shaded by dense rainforest canopies, providing a dimly lit environment rich in organic matter and insect life.

Description of Congo Tetra

The Congo Tetra is a sexually dimorphic species where males are significantly larger, more colorful, and possess extended finnage compared to the females. When kept in optimal conditions, they display a breathtaking array of shimmering colors that shift depending on the viewing angle and lighting.

Body shape:

They feature a classic, laterally compressed, and somewhat deep-bodied tetra profile, though they are noticeably bulkier and larger than most common aquarium tetras.

Color:

Their scales are highly iridescent, flashing luminous shades of blue, turquoise, green, and gold along the lateral line, fading into a silvery-violet belly.

Barbels:

They do not possess any barbels.

Snout:

The snout is relatively short and slightly rounded, equipped with small but sharp teeth adapted for eating insects and plant matter.

Eyes:

They have large, prominent eyes featuring a dark pupil surrounded by a striking, reflective silver-to-golden ring.

Fins:

Mature males develop stunning, flowing dorsal, anal, and pelvic fins that often have distinct white or violet edging. Females have shorter, more rounded fins.

The Tail:

The caudal (tail) fin is deeply forked. In adult males, the central rays of the tail fin extend outward, creating a unique, feathery appendage.

Temper

Congo Tetras are remarkably peaceful fish. Despite their larger size, they are easily startled and can be somewhat skittish if kept with boisterous or aggressive tank mates. They do best when surrounded by other calm, similarly sized species.

Sociality

This is a highly social, schooling species. They must be kept in groups of at least six individuals, though a school of eight to twelve or more will make them feel much more secure and result in a more impressive, synchronized swimming display.

Activity

They are active, mid-to-top water swimmers. During the day, they will constantly cruise back and forth across the open swimming spaces of the aquarium, frequently interacting with one another.

Keeping and Caring for Congo Tetra

While relatively hardy, Congo Tetras require pristine water conditions to truly thrive and display their best colors. They are sensitive to poor water quality and sudden fluctuations in parameters, making regular maintenance essential.

Tank size:

Due to their adult size and active swimming behavior, a minimum tank size of 30 gallons is required for a small school, though a 55-gallon aquarium or larger is highly recommended to give them ample horizontal swimming space.

Water Parameters:

Originating from river basins, they appreciate clean, well-oxygenated water that leans towards the softer, slightly acidic side.

Temperature

Maintain a stable temperature between 23-28°C (73-82°F).

pH

The ideal pH range is between 6.0 and 7.5.

Hardness

Water hardness should be kept between 3 and 18 dGH.

Ammonia, Nitrite, Nitrate

Ammonia and Nitrite must always be at 0 ppm. Nitrates should be kept as low as possible, ideally below 20 ppm, through regular water changes.

Lighting

Moderate to dim lighting is best. Bright lights can make them skittish and wash out their colors. Floating plants can be used to diffuse harsh lighting.

Water flow

They appreciate a moderate water flow that simulates the gentle currents of their native streams, providing them with exercise and well-oxygenated water.

Decorations and Plants

A dark substrate will beautifully contrast and highlight their iridescent colors. The tank should be densely planted along the back and sides to provide hiding spots, leaving a large, unobstructed open swimming area in the center. Driftwood and dried leaf litter can also be added to mimic their natural habitat.

Diet

Congo Tetras are omnivorous and generally unfussy eaters. In the wild, they feed on small insects, worms, crustaceans, and plant matter. In the aquarium, they will readily accept high-quality flakes and granules. To ensure optimal health and coloration, supplement their diet with live or frozen foods such as bloodworms, daphnia, and brine shrimp, as well as occasional vegetable matter.

Some Feeding Tips

Feed them small amounts 2 to 3 times a day—only what they can consume in a few minutes. Because they are mid-water feeders, they may ignore food once it hits the substrate, so sinking pellets or slow-sinking granules are excellent choices.

Breeding

Breeding Congo Tetras is possible but moderately difficult. They are egg scatterers and exhibit no parental care. A separate, dimly lit breeding tank with soft, acidic water and a substrate of marbles or dense moss is required to prevent the parents from eating the eggs. After conditioning the pair with live foods, spawning usually occurs in the early morning. Once eggs are scattered, the parents must be removed immediately. The fry are very small and will need infusoria or liquid fry food until they are large enough to take baby brine shrimp.

Conclusion

The Congo Tetra is a crown jewel among freshwater aquarium fish. Their dynamic schooling behavior, combined with their mesmerizing, rainbow-like iridescence and elegant fins, makes them a captivating addition to any large, peaceful community tank. With proper space, clean water, and a balanced diet, they will provide years of vibrant activity and beauty to your aquatic display.

Fish info

Care level: Easy - Moderate
Temperament: Peaceful
Adult size: 8 cm
Life expectancy: 3-5 years
Fish type: Tetra
Temperature : 23-28°C
pH: 6.0-7.5
Color Form: Blue, Gold, Green, Silver

Related on Fishs

Leave your comments

Latest on Fishs

Julidochromis transcriptus: Black-and-White Slender Cichlid

Moderate

Lake Tanganyika rock-dwelling cichlid

Julidochromis transcriptus is a small rock-dwelling cichlid from Lake Tanganyika, recognized by its compact, elongated body and irregular black-and-white pattern. It is a territorial cave dweller that is best kept as an established pair in a carefully structured aquarium. The supplied fish are identified as a DNZ pair, although sex, collection locality, and precise geographic form cannot be verified from the supplied material alone.
Azur Cichlid (Sciaenochromis fryeri) Care Guide

Moderate

Lake Malawi haplochromine cichlid

The Azur cichlid is commonly sold as Sciaenochromis fryeri, a predatory haplochromine cichlid from Lake Malawi. Mature males develop vivid electric-blue coloration, while females and juveniles are generally less intensely colored. This fish is moderately aggressive and needs a spacious aquarium with rocky structure, alkaline, mineral-rich water, and carefully selected tank mates. The supplied source describes a DNZ pair, but sex and exact locality cannot be confirmed from the images alone. Identification confidence is therefore good but not absolute.
Marble Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The marble angelfish is a captive-bred color form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its elegant fins and distinctive irregular black patterning. It needs a mature, spacious aquarium with excellent water quality, warm water and suitable tank mates. Although generally manageable, adults establish territories and may become assertive when pairing or spawning. The supplied source identifies two marble angelfish; exact lineage and strain details cannot be confirmed from the available information.
Gold Angelfish, Pterophyllum scalare

Moderate

Freshwater South American cichlid

The Gold Angelfish is an ornamental colour form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its graceful movement and parental care. It needs a mature, spacious aquarium with substantial vertical clearance, stable warm water and carefully chosen tank mates. The supplied source identifies two fish as Gold Angelfish, although the accompanying images show several angelfish colour and fin forms, so the exact appearance of the supplied specimens cannot be confirmed from the images alone.
Zebra Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The Zebra Angelfish is a selectively bred form of Pterophyllum scalare, recognised by a silvery body with several dark vertical bars and the tall, laterally compressed shape typical of freshwater angelfish. The supplied images also show other angelfish colour forms, so the exact appearance of the listed pair cannot be confirmed from the image set alone. This South American cichlid is generally manageable for experienced community keepers, but its size, territorial breeding behaviour and need for a tall aquarium should be planned for carefully.
Black Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The supplied record identifies two black angelfish, most likely a domestic color form of Pterophyllum scalare. The photographs show several angelfish color patterns, so they should not be treated as proof that every pictured fish is black or that all belong to the same strain. Black angelfish retain the tall, laterally compressed body and extended fins typical of freshwater angelfish. They need a tall, mature aquarium, stable warm water, a varied diet, and carefully selected tank mates.
White Marble Angelfish (Pterophyllum scalare)

Moderate

Freshwater cichlid

The white marble angelfish is a selectively bred aquarium color form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its elegant fins and distinctive irregular dark marbling. It is generally peaceful when young but can become territorial, especially when paired for spawning. Successful care depends on a tall aquarium, excellent water quality, suitable tank mates, and a varied carnivorous-omnivorous diet. The exact genetic strain shown cannot be confirmed from photographs alone.
Freshwater Angelfish Mix (Pterophyllum scalare)

Moderate

Freshwater cichlid

Freshwater angelfish are tall-bodied South American cichlids valued for their graceful movement and wide range of captive color forms. The supplied source identifies a mixed group as Pterophyllum scalare; the photographs show several forms, including striped, black, orange, white, silver and blue-toned fish. They are manageable for experienced beginners, but their adult height, territorial breeding behavior and tendency to eat small tank mates require thoughtful aquarium planning.
Leopard Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The leopard angelfish is a domestic color form of Pterophyllum scalare, a tall-bodied freshwater cichlid from tropical South America. Its silver to yellowish body is marked with irregular dark spots or broken vertical bars, although pattern intensity varies with age, mood and breeding line. It is generally peaceful in a suitably spacious community aquarium, but pairs become territorial when spawning. This fish needs warm, clean water, generous vertical swimming space and tank mates too large to swallow.
Yellow Labidochromis (Labidochromis caeruleus)

Easy - Moderate

Lake Malawi mbuna cichlid

The Yellow Labidochromis is a bright yellow mbuna cichlid from Lake Malawi. Labidochromis caeruleus is generally manageable for an African cichlid, but it remains territorial and needs hard, alkaline water, rockwork, and carefully chosen companions. The supplied source identifies two fish as a pair; sex and pair bonding cannot be confirmed from the available images. This species is an adaptable algae grazer, a maternal mouthbrooder, and a rewarding choice for an appropriately planned Malawi cichlid aquarium.
Blue Pearl Angelfish (Pterophyllum scalare)

Moderate

Freshwater cichlid

The Blue Pearl Angelfish is a selectively bred colour form of Pterophyllum scalare, the freshwater angelfish. Its laterally compressed body, extended fins and tall profile make it a striking inhabitant of a planted community aquarium. The supplied trade label supports identification as this species and colour form, although individual colour intensity can vary. It requires warm, stable, clean water, generous vertical swimming space and thoughtful tank-mate selection, especially as adults become territorial when pairing or spawning.
Villavicencio Dwarf Cichlid Apistogramma macmasteri

Moderate

South American dwarf cichlid

Apistogramma macmasteri, commonly called the Villavicencio dwarf cichlid, is a small South American cichlid associated with the Río Orinoco drainage of Colombia. It is valued for its compact size, elaborate finnage and interesting courtship behavior. A bonded pair can be kept in a carefully structured aquarium with soft, clean water, sand, cover and several potential spawning sites. Although manageable for an experienced community aquarist, territorial behavior increases during breeding, so tank layout and tankmate selection are important.
Neolamprologus leleupi (Tanganyika Golden Cichlid)

Moderate

Lake Tanganyika rock-dwelling cichlid

Neolamprologus leleupi is a small, brightly coloured cichlid endemic to Lake Tanganyika in East Africa. It inhabits rocky coastal areas and uses crevices for shelter, feeding and spawning. Despite its modest size, it can be strongly territorial, particularly when paired or breeding. The supplied source identifies these fish as a golden colour form and a pair, although sex cannot be confirmed reliably from the image alone. Successful care depends on alkaline, mineral-rich water, abundant rockwork and carefully chosen tank mates.
Maingano Cichlid (Melanochromis cyaneorhabdos)

Moderate - Difficult

Lake Malawi mbuna cichlid

The Maingano, or Johanni Maingano, is a Lake Malawi mbuna recognized for its intense steel-blue body and dark horizontal markings. The supplied label combines “Johanni” with the scientific name Melanochromis cyaneorhabdos; these are distinct species, so identification should be confirmed from the seller or locality. This territorial mouthbrooding cichlid needs hard, alkaline water, abundant rockwork, a predominantly algae-based diet, and careful stocking to limit aggression.
Red Chocolate Gourami (Sphaerichthys vaillanti)

Difficult

Blackwater labyrinth fish

The red chocolate gourami, Sphaerichthys vaillanti, is a specialized Southeast Asian labyrinth fish suited to mature, soft, acidic blackwater aquariums. It is peaceful but easily stressed by bright lighting, strong currents and boisterous tank mates. The supplied source identifies these fish as a pair; sex and exact identity cannot be confirmed from the image alone, so identification should be checked against a reliable specimen reference. Stable water quality, cover and a varied small-food diet are central to long-term success.
Pelvicachromis pulcher Purple Tilapia Pair Care Guide

Easy - Moderate

Small West African freshwater cichlid

Pelvicachromis pulcher, commonly called the kribensis or purple cichlid, is a small West African cave-spawning cichlid valued for its manageable size, attractive breeding colors and attentive parental behavior. A bonded pair can live in a community aquarium when provided with suitable cover and carefully chosen tank mates. The supplied listing identifies the fish as Pelvicachromis pulcher, although photographs alone cannot confirm the exact locality or color form.