Congo Tetra Care Guide

The Congo tetra breaks the 'tetra equals nano fish' rule: males reach ~8 cm and trail long, flowing grayish-violet, white-edged fin extensions that are the whole reason people buy it. It is a big, fast, easily-spooked African shoaler — buy it only for a long, calm, lidded tank, keep it in a mixed-sex group, and keep it far from fin-nippers, because here the fish is the victim, not the aggressor.

Congo Tetra at a glance

The sourced figures the welfare engine uses to judge Congo Tetra — the parseable key facts.

Where it comes from

It is endemic to the Congo River basin in central Africa — the lower and middle Congo drainage across the Democratic Republic of the Congo and Republic of Congo — living in streams, tributaries, pools and marshes. The soft, slightly-acidic-to-neutral Congo water is why it shows its best colour and finnage in soft water and why hard alkaline extremes, though tolerated, are wrong. The large-river origin is why this is an active, room-hungry swimmer rather than a nano fish, and the dappled-light, vegetated, wood-strewn biotope is why dense planting, floating cover and driftwood settle what is, by nature, a shy and skittish fish. Seriously Fish frames the ideal setup as an African biotope tank with driftwood branches, floating vegetation and anubias.

Did you know?

• A tetra that breaks the rule: males reach ~8 cm with long, flowing feathery violet-and-white tail and dorsal extensions — one of the largest, most ornate 'tetras' in the hobby, needing a four-foot tank.
• African, not Amazonian — unlike the famous neon and cardinal, it is endemic to the Congo River basin (DRC and Republic of Congo), described by George Albert Boulenger in 1899.
• The fins are the whole point and the whole risk: the prized male finnage only develops fully in a calm, spacious, nipper-free tank — stress and nipping literally stunt the feature people buy the fish for.
• A prolific spawner — a single female can drop 300–500 large, sinking eggs in one go.
• It is the fish being protected by its tankmate exclusions: known fin-nippers are kept out of its suggestions precisely because it is fin-nippable, not a nipper.
• Conservation status: IUCN Least Concern (assessed 2009).

Tank size — and why

The headline constraint is length, not gallons. Seriously Fish calls for a 48 x 12 x 12 inch (120 x 30 x 30 cm) tank for adults and FishBase a 100 cm minimum, whereas a standard US 30-gallon is only about 36 inches (91 cm) long — shorter than recommended. So a 48-inch tank (commonly 40–55 US gallons in standard sizing) is the real floor; the gallon figure alone understates the footprint this fish needs. The reason is the fish itself: a large (males ~8 cm), fast, active swimmer that needs a long open lane. AquariumStoreDepot is blunt — a 20-gallon with four Congo tetras is a recipe for stressed, dull fish with damaged fins. A tight-fitting lid is essential, especially in the first weeks: newly added Congos are nervous, jumpy and prone to dashing into the glass.

As a guide, a 55-gallon tank comfortably suits about 6–9 Congo Tetra as a single-species display, leaving room for tankmates.

How big does it really get?

Full-grown Congo Tetra reach about 8 cm (3.1 in) long, but they are usually sold at only about 2.5 cm (1 in) — a typical shop size (estimate). At full size, Congo Tetra needs roughly a 55-gallon tank, about 122 cm long; a common 10-gallon starter kit is only about 51 cm.

Adult size is sourced; the shop size is a typical-juvenile estimate; tank length is approximate for a standard 55-gallon aquarium.

Water parameters in practice

Target about 24–27 °C, comfortable across 23–28 °C (FishBase narrower at 23–26). Keep the water soft and slightly acidic, around pH 6.0–6.5 — the species tolerates up to neutral or slightly alkaline (FishBase's ceiling reaches 8.0), but that is tolerance, not a target, and soft acidic water is where colour and breeding happen. Hardness is best soft to moderately soft, roughly 3–12 dGH, kept below about 18 dH. For this nervous fish, stable parameters and good cover matter more than chasing exact numbers, and soft acidic water specifically is important for the male finnage and for breeding.

Diet & feeding

An omnivore and micropredator — in the wild it takes worms, small insects, crustaceans, algae and zooplankton (trophic level 3.0). It is an enthusiastic, non-fussy feeder, so a good-quality flake or pellet makes the base, supplemented with live and frozen foods (brine shrimp, daphnia, tubifex, bloodworm) and some vegetable matter to boost colour and condition the males' finnage and breeding females. Feed small amounts once or twice a day; underfeeding pushes them to nip soft and carpeting plant leaves. These are fast, confident mid-water feeders that out-compete shy, slow tankmates — another reason not to pair them with timid nano fish that get out-eaten.

Gear & setup

A heater to hold the mid-20s, moderate flow to suit the river origin, and a densely planted layout with open swimming space, driftwood and floating plants for shade — cover the fish can retire to when startled is what tames its skittishness. Dark substrate intensifies the iridescent colour. Choose tougher plants such as anubias and java fern, both because they suit a low-light biotope and because hungry Congos nip softer or carpeting leaves. A tight lid is not optional: this is a leaping, glass-dashing fish when newly added or spooked.

Temperament & behaviour

Peaceful toward other species and not a fin-nipper itself — but it is a shy, easily-frightened fish, especially when not kept in numbers. It is easily startled and dashes or jumps when spooked, so it needs calm tankmates, dense cover and a good shoal as security. Minor intra-male sparring exists but is managed by a female-skewed ratio; the top-level temperament is genuinely peaceful. In a proper shoal and a long calm tank it becomes active and glittering with fully-developed male fins; under-stocked or in a short, rowdy tank it hides, fades, gets nipped and turns jumpy.

Group & social needs

Must be kept in a mixed-sex shoal. FishBase floors it at five or more and hobby consensus at six-plus, but the welfare detail is the sex ratio: aim for roughly two females per male to reduce aggression, and note that fewer than six males stop displaying properly. A larger shoal gives bolder fish and the full male fin display; a small or all-male group leaves males sparring, faded and fin-stressed.

Compatible tank mates (preview)

A short, engine-cleared shortlist — the species TankStocking's welfare engine clears with Congo Tetra and that suit its size and temperament best. Tap any to load the pairing in the planner.

• Amano Shrimp — Peaceful temperament, similar adult size, not a fin-nipper.
• Bamboo Shrimp (Wood/Fan Shrimp) — Peaceful temperament, similar adult size, not a fin-nipper.
• Bleeding Heart Tetra — Peaceful temperament, similar adult size, not a fin-nipper.

A note on the shrimp and snails here: Congo Tetra is peaceful and generally invertebrate-safe — but almost any fish will take very small shrimplets given the chance, so give shrimp dense cover (moss, leaf litter) if you want a colony to grow, rather than expecting every baby to survive.

This engine-cleared shortlist is Congo Tetra's tankmate surface for now — a dedicated tank-mates guide can follow for high-demand species.

Breeding & sexing

Sexing is easy in adults: males are larger, far more colourful, and carry the long extended caudal and dorsal filaments, while females are smaller, plainer and plumper when gravid. Difficulty is moderate — possible at home with effort, with fry survival best in a dedicated breeding tank. Use soft slightly-acidic water (around pH 6.0–7.5) at roughly 24–27 °C, often over a peat-moss substrate, and condition on live foods; sexual maturity comes at about 9–12 months. It is a prolific egg-scatterer — a female drops up to 300 eggs (hobby sources cite up to ~500) which are large, adhesive and sink to the bottom — and parents eat the eggs, so remove the adults. Eggs hatch in about 6–7 days; start fry on infusoria and microscopic foods, then baby brine, kept dim and clean.

Lifespan

Typically 3–5 years in captivity, consistent across hobby sources. What shortens it is stress from a too-small or rowdy tank, fin damage from nippers, hard or unstable water, too small a group (males stop displaying and fade), and chronic skittishness from inadequate cover or length.

Common mistakes

• Treating it like a small tetra in a small tank. It is a fast 8 cm fish that needs a 120 cm / 48-inch long tank; a 30-gallon (36-inch) or 20-gallon is too short and produces stressed, dull, fin-damaged fish.
• Housing it with fin-nippers or boisterous fish. The long male fins are prime targets — tiger barbs, serpae tetras and black-skirt tetras are exactly the kind of nippers that shred them, and the shy fish then hides. This is the single most-repeated warning, and the reason those species are excluded from its tankmate suggestions.
• Too small or all-male a group. Under six, or with no females, males stop displaying, colour fades and sparring rises — keep 6+ mixed-sex at about two females per male.
• No lid. Newly added Congos are jumpy and dash into the glass; a tight lid is essential in the first weeks.
• Hard alkaline water and no cover — it wants soft slightly-acidic water and a planted, shaded, wood-strewn layout to feel secure.
• Underfeeding — hungry Congos nip soft and carpeting plants.

Signs of trouble

• Faded, washed-out colour and hiding — chronic stress from too small a group, too short a tank, or boisterous tankmates.
• Clamped or eroding fins, especially on the long male extensions — fin damage from nipping tankmates or rough décor, which also prevents the prized finnage developing.
• Dashing into the glass or jumping — a startled, insecure fish; check cover, numbers and the lid.
• Males ceasing to display — an early signal the group is too small or the tank too cramped or rowdy.

Is this fish right for you?

Don't buy Congo tetras if you only have a tank shorter than about 48 inches / 120 cm, if your community has fin-nippers (tiger barbs, serpae or black-skirt tetras) or aggressive, large or predatory fish, if you can't keep a mixed-sex shoal of six or more, or if you can't provide soft, stable, planted, lidded conditions. It is hardy and easy to feed, but it is not a casual first-tank nano fish. Choose stock with intact, well-developed fins, full colour and active behaviour; skip timid, faded or fin-damaged fish. There is no common dyed or balloon morph issue for this species.

Bringing one home

Float to equalise temperature, then add tank water gradually before netting the fish across, and keep a tight lid on from day one — newly added Congos are at their jumpiest in the first weeks and will dash into the glass. Add them to a mature, soft, stable, planted tank with cover, quarantine new stock, and give them numbers immediately so they settle rather than hide.

Common questions

What size tank do Congo tetras need?

The constraint is length, not gallons. Seriously Fish recommends a 120 cm / 48-inch tank and FishBase a 100 cm minimum, while a standard 30-gallon is only ~36 inches long — too short. Plan on a 48-inch tank (commonly 40–55 US gallons) for a proper shoal of these fast 8 cm fish.

Are Congo tetras fin-nippers?

No — it's the other way round. The Congo tetra is peaceful and does not nip, but its long flowing male fins are prime targets for nippers like tiger barbs, serpae tetras and black-skirt tetras, which shred them. Keep it away from fin-nippers; that's why those species are excluded from its tankmate suggestions.

How many Congo tetras should I keep, and what ratio?

Keep a mixed-sex shoal of at least six. Aim for roughly two females per male to reduce aggression and let the males display; fewer than six males tend to stop displaying and fade. A bigger shoal in a long calm tank brings out the best colour and finnage.

Are Congo tetras good for beginners?

They are hardy and easy to feed, but they are not a casual first fish. They need a four-foot tank, a mixed-sex shoal, a tight lid (they jump), soft stable water and no fin-nippers. Manageable, but plan the tank around them.

What water do Congo tetras need?

Soft, slightly acidic water around pH 6.0–6.5 (tolerated up to neutral/slightly alkaline) at about 24–27 °C, with hardness roughly 3–12 dGH. Soft acidic water gives the best colour and is needed for breeding; stability and cover matter most for this nervous fish.

Sources & confidence

Sources & confidence (9 species)

These back the Congo Tetra figures and the previewed tank mates above. Each figure is read from the TankStocking species database (v2026.06); below is the care reference behind it and how confident we are in that data. Confidence reflects the source quality, not whether any pairing is safe. Full source list and the welfare model are on the methodology page.

• Congo Tetra Phenacogrammus interruptus — Seriously Fish (seriouslyfish.com/species/phenacogrammus-interruptus) high confidence
• Amano Shrimp Caridina multidentata — Aquarium Co-Op amano shrimp care; Aquadiction high confidence
• Bamboo Shrimp (Wood/Fan Shrimp) Atyopsis moluccensis — Aquariadise (aquariadise.com/caresheet-bamboo-shrimp-atyopsis-moluccensis) high confidence
• Bleeding Heart Tetra Hyphessobrycon erythrostigma — Seriously Fish (Hyphessobrycon erythrostigma) high confidence
• Boesemani Rainbowfish Melanotaenia boesemani — Seriously Fish; Aquarium Co-Op Boesemani guide high confidence
• Bolivian Ram Mikrogeophagus altispinosus — Seriously Fish (seriouslyfish.com/species/mikrogeophagus-altispinosus) high confidence
• Brilliant Rasbora Rasbora einthovenii — Seriously Fish (seriouslyfish.com/species/rasbora-einthovenii) high confidence
• Bristlenose Pleco Ancistrus sp. — Aquarium Source / aqua-fish.net Ancistrus care guides high confidence
• Bronze Corydoras Corydoras aeneus — Seriously Fish (seriouslyfish.com/species/corydoras-aeneus) high confidence

Care-guide sources (6)

This guide synthesises the references below; where they disagree, the range and the disagreement are noted in the text above. The figures in the key-facts box are read from the TankStocking species database (v2026.06). Full welfare model on the methodology page.

• FishBase — Phenacogrammus interruptus — authority (Boulenger 1899), family Alestidae, lower/middle Congo basin range, benthopelagic, max male 8.0 cm TL / female 6.0 cm, temp 23–26 °C, pH 6.0–8.0, dH 5–19, omnivore diet, trophic 3.0, groups of 5+ / min 100 cm, up to 300 sinking eggs / hatch ~6 days, IUCN Least Concern (2009)
• Seriously Fish — Phenacogrammus interruptus — Congo drainage (DRC), African biotope setup, male 8 cm / female 6 cm, min tank 48x12x12 in (120x30x30 cm), temp 23–28 °C, pH 6.0–7.5, hardness 3–18 dH, omnivore, peaceful but active ('may scare shy species'), 'easily frightened… if not maintained in numbers', mixed-sex shoal, sexing, 'Do not keep congo tetras with fin-nipping species', egg-scatterer up to 300 eggs
• Wikipedia — Congo tetra — Boulenger 1899, Alestidae, central Congo River basin, male ~7.6 cm / female ~7.0 cm, grayish-violet feathery white-edged tail, breeding (soft slightly acidic pH 6.0–7.5, 24–27 °C, several hundred eggs, hatch 6–7 days, maturity 9–12 months), IUCN Least Concern
• AquariumSource — Congo Tetra 101 — size 3–3.5 in captive / 4.5 in wild, lifespan 3–5 years, min tank 30 gal, temp 72–82 °F (target 76 °F), pH 6.0–7.5 (lower end), hardness 3–18 dGH, group 6+, omnivore + veg, skittish with aggressive fish, sexing, breeding up to 500 eggs
• ModestFish — Congo Tetra care — 30 gal min, size 3–3.5 in, lifespan 3–5 years, temp 72–82 °F, pH 6.0–7.5, group 6+ schooling, nips carpeting plants, tankmate list
• AquariumStoreDepot — Congo Tetra Complete Care Guide — '20-gal with 4 = stressed, dull fish with damaged fins', lifespan 3–5 years, temp 73–82 °F, pH 6.0–7.5, hardness 3–18, group 6+ at '2 females per male', 'newly added Congo tetras are nervous, jumpy… a tight-fitting lid is essential', fins vulnerable to nipping, avoid-list (bucktooth/tiger barb/flowerhorn/wolf cichlid/oscar/jaguar), breeding ~500 eggs

More on Congo Tetra

Related guides on TankStocking — each scored by the same welfare engine as the planner.

This care guide is a sourced planning reference, not veterinary advice — individual fish, filtration and maintenance all matter. Cycle the tank, test your water, and observe your fish. How TankStocking works →