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title: "Congo Tetra: The Complete Care, Tank & Breeding Guide" description: "The definitive Congo tetra (Phenacogrammus interruptus) care guide: soft water parameters, tank setup, the iridescent finnage, feeding, peaceful tank mates, and breeding." slug: congo-tetra commonName: Congo Tetra scientificName: Phenacogrammus interruptus family: Alestidae order: Characiformes difficulty: Intermediate minTankSize: 40 temperature: "75–81°F (24–27°C)" ph: "6.0–7.5" hardness: "3–15 dGH" lifespan: "3–5 years" maxSize: "4.5 inches (11 cm) males" origin: "Democratic Republic of the Congo" publishedAt: "2026-06-04"

Congo Tetra: The Complete Care, Tank & Breeding Guide

The Congo tetra is the showpiece of the African characin world — a large, shimmering tetra whose pearlescent body flashes blue, gold, and red as it catches the light, and whose mature males trail soft, feathered fin extensions that ripple as they swim. Phenacogrammus interruptus brings a scale and elegance few tetras can match, schooling gracefully through a planted, dimly-lit tank. It's peaceful and rewarding, with two keys to success: keep it in a proper group, and protect its delicate flowing fins from nippers.

This guide is the complete reference: the Congo tetra's African biology, the soft water it prefers, how to set up its tank, what to feed it, which tank mates suit its fins, and how to breed it.

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Species Overview

The Congo tetra (Phenacogrammus interruptus) is a characin in the family Alestidae (the African tetras), native to the Congo River basin. It is large for a tetra — males reach about 11 cm (4.5 inches) including fins, females a little smaller — with a tall, laterally compressed body covered in iridescent scales that shimmer blue at the top, gold through the middle, and reddish below, shifting with the light. Mature males develop the species' signature feature: soft, greyish-white, feathered extensions to the central tail and the dorsal fin, giving them a flowing, almost ragged elegance.

The Congo tetra is peaceful, shoaling, and graceful, but somewhat skittish, so it needs a roomy, planted, calm tank and a group to feel secure. It's rated intermediate for its size (needing a larger tank), its preference for soft, warm water, and the care needed to protect its long fins from nippers. With good care it lives 3–5 years, and a mature shoal drifting through a dark planted tank is one of the most beautiful sights in freshwater fishkeeping.

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Natural History and Origin

Phenacogrammus interruptus is endemic to the Congo River basin in central Africa, living in soft, slightly acidic, often tannin-stained streams, tributaries, and pools with subdued light and plenty of vegetation and submerged structure. This soft, warm, dim African blackwater-leaning habitat shapes its care: it shows its best iridescence and feels most secure in soft, warm, gently acidic, dimly-lit water.

In the wild, Congo tetras form large shoals in the middle and upper water, feeding on insects, crustaceans, plant matter, and other small foods. Their skittish nature is an anti-predator adaptation — in open African waters they rely on grouping and quick flight — which translates into a need for cover, calm tank mates, and a proper group in the aquarium. Most Congo tetras in the trade are now tank-bred, hardy, and reasonably adaptable, though they always look best in soft, dim, planted conditions that recreate their home.

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Water Parameters

Congo tetras do best in soft, warm, slightly acidic, stable water reflecting their Congo origins, though tank-bred fish tolerate moderately hard water. Keep the tank cycled and stable — confirm with the nitrogen cycle tracker and check values with the water parameters reference. Soft, gently tannin-stained water (from driftwood and botanicals) deepens their iridescence and helps the somewhat-sensitive fish feel at home.

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Tank Setup Guide

Tank size

Because they reach 11 cm and are active, skittish swimmers, Congo tetras need a minimum of 40 gallons (150 litres), with 55+ gallons better, and length matters for their shoaling. Always keep a group of at least 6, ideally more, with a balance of males and females.

Aquascape — planted, dim, with swimming room

Congo tetras want a planted tank with subdued lighting and open swimming space. Use background and side planting, driftwood, and a dark substrate, with leaf litter/botanicals for gentle tannins, leaving the central water column clear for the shoal. Dim lighting (helped by floating plants like duckweed) is important: it makes these skittish fish feel secure and dramatically enhances their iridescence — bright, open tanks leave them nervous and washed-out.

Filtration, flow, lid

Use reliable filtration with gentle-to-moderate flow and provide a secure environment with cover and sightline breaks to settle their nerves. A lid is important — skittish Congo tetras can jump, especially when startled. A calm, dim, planted, roomy tank brings out their full beauty and confidence.

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Feeding Guide

Congo tetras are omnivores with hearty appetites that take a wide variety of foods.

What to feed

• Quality flake and pellets — a convenient staple (they're large enough for standard sizes).
• Live and frozen daphnia, baby brine shrimp, and bloodworm — relished, excellent for colour and conditioning.
• Some vegetable/spirulina content for balance — they take plant matter in the wild.

How often

Feed two to three meals daily. A varied diet brings out the males' full iridescence and encourages the development of their flowing finnage. Being skittish, they may dash off when first approached but quickly learn feeding routines. A healthy Congo tetra is full-bodied, shimmering, and shoaling confidently in the open.

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Behavior and Temperament

Congo tetras are peaceful but skittish — graceful, active shoalers that drift through the middle and upper water, their iridescence flashing as they turn. A proper group of 6 or more is essential: in small numbers they become nervous, shy, and prone to dashing, while in a good shoal they're confident and display their best colour and the males' flowing fins. Males may gently display to one another with raised fins and intensified shimmer, generally without harm, especially in a spacious planted tank.

Their nervousness means sudden movements or boisterous tank mates can startle them into jumping or hiding, so a calm tank with cover, dim light, and gentle companions is key. They are completely peaceful toward other species. Given the right roomy, planted, calm environment, Congo tetras are serene, shimmering, and elegant — a standout centerpiece schooler with a presence few tetras can match.

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Compatibility

Congo tetras suit a peaceful, soft-water community of calm fish that won't nip their delicate fins.

Good tank mates: boesemani rainbowfish, pearl gourami, kribensis, bolivian ram, bristlenose pleco, corydoras, siamese algae eater, peaceful larger rasboras and tetras, and other calm community fish of similar size.

Cautions:

• Fin-nippers (tiger barb, serpae tetra) — will shred the males' delicate flowing fins; the single most important thing to avoid.
• Aggressive cichlids or boisterous fish — startle and stress the skittish Congos.
• Very small fish — may be intimidated by (though rarely eaten by) the larger Congos.

Because their long fins are vulnerable, no fin-nippers is the golden rule. Use the compatibility checker and favour calm, similarly-sized tank mates.

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Breeding Guide

Breeding Congo tetras is moderately challenging and rewarding, requiring soft water and good conditioning. They are egg-scatterers. Sexing is easy in mature fish: males are larger, more iridescent, and have the long feathered fin extensions; females are smaller, rounder, and plainer.

Condition a group well on rich live foods, then set up a separate breeding tank with very soft, slightly acidic water, dim lighting, and fine-leaved plants or a spawning mop over a protective mesh or marbles. Spawning often occurs in the morning light: the pair scatters a large number of relatively big eggs among the plants/substrate. Remove the adults afterward, as they eat the eggs. The eggs are somewhat slow to hatch (a week or so), and the fry are reared on infusoria and then microworms and baby brine shrimp in soft, clean water. Soft water is essential for fertile eggs and successful development, making this a satisfying project for keepers with soft tap water or RO capability.

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Health and Disease

Congo tetras are reasonably hardy in good conditions, with most problems traced to stress, hard or unstable water, and fin damage.

Ich can follow temperature swings or the stress of being newly added or kept in too-small a group; treat promptly. Bacterial infections and fin rot follow poor water or — commonly — fin damage from nippers or jumping, which then becomes infected. Stress-related decline results from inadequate group size, bright bare tanks, or boisterous tank mates. Fungal issues can follow injury.

Prevention: a stable, cycled, soft-ish, warm, dim, planted tank; a proper shoal; calm tank mates with no fin-nippers; a secure lid; a varied diet; and quarantine of new arrivals. Protect those flowing fins, keep the fish calm and grouped, and the Congo tetra is a robust, beautiful, long-lived centerpiece.

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Interesting Facts

• An African tetra. Unlike the famous South American tetras, the Congo tetra hails from the Congo basin and belongs to the African characin family Alestidae.
• Feathered finnage. Mature males develop soft, greyish, feathered extensions to the tail and dorsal fin — unique flowing elegance among tetras.
• A living rainbow. Its iridescent scales shift through blue, gold, and red as the light catches them, especially against a dark, dim backdrop.
• Skittish by nature. Its nervousness is an anti-predator trait from open African waters — hence the need for cover, calm, and a proper group.
• Big for a tetra. At up to 11 cm, it brings a scale and presence most tetras can't, needing a larger tank to match.

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Bringing It Together

The Congo tetra is the shimmering, elegant showpiece of the tetra world — a large, iridescent, feathery-finned African characin that, kept in a proper group in a soft, warm, dimly-lit planted tank, becomes a living rainbow drifting through the water. Give it a 40-gallon-plus planted tank with subdued lighting, soft slightly-acidic water, gentle flow, a secure lid, a varied diet, and calm tank mates with absolutely no fin-nippers — and keep a shoal of 6 or more with both sexes — and it will reward you with serene, shimmering beauty and, very possibly, a soft-water spawn. It pairs beautifully with boesemani rainbowfish, pearl gourami, and kribensis. Plan the build with the AI Tank Blueprint generator and the compatibility checker.