Tetras & rasboras · Intermediate care

Congo tetra

Phenacogrammus interruptus

Congo tetra is rated intermediate here because of its adult size, water range and social needs. Use plants or wood for cover while leaving room for the school to move. Needs open swimming room and a secure lid; males develop flowing fins.

Congo tetra (Phenacogrammus interruptus) in an aquarium
Photo: André Karwath aka Aka · CC0
Adult size8 cm (3.1 in)
Minimum tank40 US gal
Temperature73–82°F (23–28°C)
pH range6.0–7.5
Group size6+ fish
Swimming levelMiddle to upper

Is Congo tetra a good aquarium fish?

Congo tetra reaches about 8 cm as an adult, so plan around the adult fish rather than the juvenile size seen in shops. The suggested minimum of 40 US gallons assumes suitable filtration, open swimming space and routine maintenance.

Generally peaceful in a suitable community. Keep the recommended group of at least 6 fish and avoid mixing it with tank mates that need a very different temperature, water chemistry or swimming level.

Water and aquarium setup

A stable temperature of 23–28°C and pH of 6.0–7.5 are the working ranges in the planner. Stability and clean, oxygenated water matter more than chasing a single target number.

Use plants, wood or rock to create cover while leaving the open swimming space this species needs.

Diet

Small community-fish pellets or flakes, supplemented with frozen or live foods.

Compatibility notes

Needs open swimming room and a secure lid; males develop flowing fins.

Use the Stocking & Bioload Planner to check a proposed community. Its estimated bioload value for one adult congo tetra is 3.24 units; this is a planning heuristic, not a replacement for testing nitrate.

Common mistakes

  • Planning around the shop size instead of the adult size.
  • Adding a schooling fish in a group smaller than its social minimum.
  • Ignoring the tank's length, floor area or lid because the gallon number looks adequate.
  • Adding fish before the aquarium is cycled and ammonia and nitrite are consistently zero.

Care ranges are conservative summaries of commonly cited husbandry references. Individual fish, strains and local water can differ; monitor the aquarium and adjust the plan gradually.

Photo source: André Karwath aka Aka · CC0. The local copy is resized for page performance.