Congo Tetra 4cm (Pair)

Most tetras are colourful. The Congo Tetra is theatrical. A juvenile looks like a plain silver fish and gives away nothing. Give it eighteen months, a long tank and a dark substrate, and it turns into a shifting band of blue, gold, green and rose that changes colour depending on where you stand.

Mature males grow long, flowing extensions on the dorsal and tail fins — the middle caudal rays stretch out into a distinctive dark plume that no other commonly kept tetra has. At around 8 cm they are substantially bigger than a Neon or Rummynose, but the temperament is the same: peaceful, shoaling, and completely non-aggressive toward tank mates. A settled school of adults moving through open water is one of the genuine showpiece displays in freshwater.

Care Snapshot

Scientific name	Phenacogrammus interruptus
Family	Alestidae — African tetras
Origin	Tank-bred; native to the Congo River basin, DR Congo
Adult size	Males 8 cm · Females 6 cm
Size on arrival	Approx. 3–4 cm
Lifespan	3–5 years
Minimum tank	150 litres, minimum 90 cm length
Temperature	23–28 °C
pH	6.0–7.5 — slightly acidic preferred
Hardness	4–8 dKH
Diet	Omnivore — dry, frozen and live foods
Temperament	Peaceful, shoaling; keep 8+
Care level	Easy — hardy and adaptable
Swimming zone	Top and middle, feeds at all levels

Setting Up For It

• Length matters more than volume. This is a strong, constant swimmer. A tall 150-litre cube is worse for it than a long 120 cm tank. Leave the front two-thirds open and push planting to the back and sides.
• Dark substrate, dim light, floating cover. Under bright light over pale gravel it stays washed-out and skittish. Dark sand plus a partial screen of floating plants is the single biggest difference between a dull Congo Tetra and a spectacular one.
• Tannins and leaf litter. The natural habitat is soft, acidic blackwater. Catappa leaves and driftwood deepen the iridescence and settle the fish noticeably.
• Keep the tank covered. Congo Tetras spook and jump, particularly in the first fortnight and if the room light is switched on suddenly in a dark room. A tight lid is not optional.
• Moderate flow is welcome. Unlike most soft-water tetras, this one appreciates a bit of current and will swim into it.

Tank Mates

Note: a nervous, under-stocked group of three or four Congos may nip each other's fins. This stops once the school is large enough.

Feeding

Not a fussy eater, but the mouth is surprisingly small for the size of the body — keep particle sizes modest even on adults. Colour and finnage respond directly to diet quality, so this is not a species to run on flake alone.

From the AQA range, use a colour-enhancing community pellet or flake as the daily staple, twice a day, and rotate in a frozen or freeze-dried meaty food two or three times a week. Feed only what the school clears in around two minutes.

Foods it responds to particularly well: frozen bloodworm, brine shrimp, daphnia, mysis, and live blackworm as a conditioning food.

Sexing & Breeding

Males are larger, deeper-bodied, far more iridescent, and grow extended dorsal and anal fins plus the characteristic elongated middle rays of the tail. Females stay smaller, rounder and mostly silver-green with plain fins. Neither sex is reliably distinguishable below about 4 cm.

Breeding is possible but not casual. Condition a pair or trio heavily on live food, then move them to a dim, soft, acidic tank with a spawning mop or fine-leaved plants over a mesh base. Eggs are scattered loosely and are unusually light-sensitive, so keep the tank shaded. Hatching takes around six days — longer than most tetras — and the parents will eat the eggs, so remove them after spawning.

Keeping It In Indian Conditions

• Room temperature across most of India sits inside the 23–28 °C range for much of the year, so no heater is needed except in northern and hill-station winters. Set one to 24 °C where night-time dips are common.
• Summer is the real constraint. Above 30 °C, oxygen falls and this active, oxygen-hungry species is among the first to show it — surface gasping and lethargy. Add surface agitation and a fan across the water in peak heat.
• Hard, alkaline municipal water is tolerated well by tank-bred stock, but colour never reaches its peak in it. Catappa leaves, driftwood, or blending in some RO water gets you the blues and golds the species is bought for.
• Because full colour takes 12–18 months, this is a species worth buying young and growing on. Adults are rarely available and command a considerable premium.