Congo Tetra Complete Care Guide: Phenacogrammus interruptus
The Congo tetra is the exception to the small-tetra rule — a 7-8 cm African characin with iridescent scales and flowing veil fins that needs a 75 cm tank and a well-thought-out aquascape to show at its best. This congo tetra complete care guide covers Phenacogrammus interruptus from tank size through flow management, planting and the challenges of sourcing healthy specimens in Singapore. Written by the team at Gensou Aquascaping, 5 Everton Park, with over 20 years of hands-on experience in larger tetra display tanks.
Species Profile
Phenacogrammus interruptus is endemic to the Congo River basin — clear, fast-flowing streams and river margins. Adults reach 7-8 cm for males and 5-6 cm for females. Males develop extended dorsal, anal and caudal fin filaments with a blue-green-gold-orange iridescence across the flanks. Females stay duller and shorter-finned. Lifespan is four to six years in properly sized tanks.
Tank Size — Why 75 cm Is the Floor
Minimum tank length is 75 cm, minimum volume 150 litres for a school of six. Better is 90-100 cm and 200+ litres for eight fish. Congo tetras cruise continuously and cramp visibly in shorter tanks, developing frayed fins, faded colour and listless behaviour within a month. This is the single most common Congo-keeping mistake in Singapore HDB living rooms — stocking them in a standard 90-litre community tank. Browse the aquarium tanks and cabinets range for 90-120 cm rimless options.
Schooling Numbers
Minimum six fish, eight to ten preferred, with a male-to-female ratio of 1:2 or 1:3. Males display and chase each other constantly; without enough females they bully the subordinate males until only the alpha retains full fin. A school of eight (three males, five females) in a 200-litre tank is the balance point most keepers find works long-term.
Water Parameters
Temperature 23-27 degrees Celsius, pH 6.0-7.2, GH 3-8, KH 1-4. Moderately soft, slightly acidic — Singapore tap water post-dechlorination works well. An aquasoil substrate brings pH to the preferred lower band. Nitrate under 20 mg/L; Congo tetras are sensitive to chronic nitrate accumulation and show it through stalled fin development in young males.
Tank Setup
A river-biotope style with a sand substrate, a scattering of river stones along the floor, two pieces of driftwood angled with the current, and tall background plants suits this species perfectly. Congo tetras occupy mid-to-upper water column and need open swimming volume — at least 40 cm depth of unobstructed water in front of the hardscape. Source substrate from the decoration and substrate range.
Filtration and Flow
Canister filter turning 5-6x tank volume per hour, distributed via spray bar across the full width. Congo tetras come from flowing rivers and noticeably tighten their schooling and brighten their colour in tanks with perceptible current. Add a wavemaker or small circulation pump on the side opposite the canister return if the tank is over 90 cm to prevent dead zones. Browse the filtration range for canister options.
Planting Plan
Tall background stems (Vallisneria, Hygrophila polysperma, Limnophila sessiliflora) for height and movement in the current. Anubias and java fern on driftwood. Leave the mid-water volume open — Congo tetras need the swimming room. Avoid delicate carpet plants; the constant movement stirs up fine-leaved foregrounds. Visit the live plants range.
Feeding
Congo tetras are enthusiastic eaters of anything that fits their relatively large mouths. Quality flake or larger pellets (Hikari Tropical Micro Pellets graduating to standard flake), frozen bloodworm, mysis, brine shrimp, daphnia and occasional chopped earthworm. Feed twice daily, reasonably generous pinches. Males develop peak colour and fin extensions on a varied protein-rich diet. Pick up pellets and frozen from the fish food and feeding range.
Tank Mates
Compatible: medium-sized community fish — Australian rainbowfish, larger rasboras (harlequin), peaceful West African cichlids (kribensis), bristlenose pleco, larger corydoras (sterbai). Avoid fin-nippers (serpae, tiger barbs), angelfish (nibble back on Congo fin filaments), and aggressive cichlids. A species-focused display with eight Congos, a group of kribensis and a bristlenose pleco works beautifully.
Sourcing in Singapore
Congo tetras appear irregularly at Iwarna and the larger Serangoon North shops at SGD 4-8 per fish for juveniles, SGD 10-15 for fully-grown coloured-up males. Imported from Thai and European farms; quality varies significantly batch to batch. Examine fin integrity carefully before buying — a shop-held Congo with already-frayed trailing fins rarely regrows them fully. Carousell has occasional adult trade-ins from keepers downsizing, often at good prices. Budget for the correct tank size first — a properly-sized Congo tetra setup costs SGD 500-800 before fish.
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Still Have Questions About Your Tank?
Drop by Gensou Aquascaping — most walk-in questions get answered in under 10 minutes by someone who has set up hundreds of tanks.
5 Everton Park #01-34B, Singapore 080005 · Open daily 11am – 8pm
