Congo Tetra (Phenacogrammus interruptus)

Common Name

Congo Tetra

Origin and Habitat

Congo Tetras are native to the Congo River drainage in Central Africa. They are commonly associated with inland rivers and quieter zones with lots of benthic and floating vegetation, plus driftwood and submerged branches that soften the current and light.

Biotope and Natural Setup

If you want a true Congo basin feel, build the tank around soft light, dark structure, and a clear runway of open water for schooling.

Use a longer footprint and leave the center open for swimming. Then build the edges with driftwood, root tangles, and rounded stones, and let plants do the shading. A darker substrate and a mild tannin tint help their colors glow without blasting the tank with bright lighting.

Leaf litter can be used lightly for a natural look. Indian almond leaves, oak leaves, or beech leaves all work. Start small and adjust based on your filtration and how much tint you want.

These are strong, believable plant choices for a Congo style setup that also do well in aquariums:

• Bolbitis heudelotii
• Anubias congensis
• Anubias barteri varieties
• Crinum natans
• Tiger lotus, Nymphaea species
• Floating plants like water lettuce or frogbit for shade

Biotope appropriate companion fish ideas, with size and temperament matched:

• African glass catfish, Pareutropius debauwi
• Freshwater butterflyfish, Pantodon buchholzi, only with a tight lid
• Calm bushfish, Ctenopoma species, chosen carefully

Avoid known fin nippers. Mature male Congo Tetras have long fins that are part of the whole appeal, and nipping will ruin the look and stress the fish.

Temperature and Water Conditions

Congo Tetras do best in clean, stable water with good oxygenation.

• Temperature: 23 to 28°C, 73 to 82°F
• pH: 6.0 to 8.0, with many keepers aiming slightly acidic to neutral for display
• General hardness: roughly 5 to 19 dGH

Tropical Fish Co. note: We do not recommend chasing perfect numbers for day to day care. Focus on consistency, oxygenation, and water quality. Save strict parameter targeting for specific breeding goals.

Appearance and Size

Congo Tetras are one of the most iridescent classic community fish. Mature males develop longer flowing fins and throw metallic blues, golds, reds, and violet tones that shift every time they turn under light. Females are usually a bit smaller with shorter fins and a softer shimmer.

Diet in the Wild

In nature they feed on small invertebrates such as worms, insects, and crustaceans, plus some plant matter.

Feeding in Captivity

They thrive on variety. Use a quality flake or small pellet as a base, then rotate in frozen or live foods like brine shrimp, daphnia, mysis, and bloodworms. Color and fin condition usually improve fast when the diet is not repetitive.

Behavior and Tank Setup

Congo Tetras are peaceful schooling fish that look and act their best in a real group. A longer tank with open swimming space is the secret, with plants and wood along the edges so they can retreat when they want cover.

They are often described as shy in small numbers. In a larger group they become confident and you see more natural schooling behavior and better color.

Breeding

Congo Tetras are egg scattering fish with no parental care. Condition adults well on high quality foods, then provide warm, soft water with lots of fine plants or spawning media. Remove the adults after spawning to protect the eggs. Females can lay about 300 eggs, sometimes more, and eggs typically hatch in about 6 days.

Breeder’s Tips

• Use a spawning mop or dense fine plants so eggs fall out of reach
• Keep lighting dim to encourage spawning behavior
• Move parents out right after you see spawning
• Start fry on infusoria or other microscopic foods, then baby brine shrimp as soon as they can take it
• Gentle, frequent small water changes beat big swings

Quick Facts

• Adult size
  Males commonly around 7.6 to 8 cm, about 3.0 to 3.1 in. Females commonly around 6 cm, about 2.4 in.
• Lifespan
  Often about 3 to 5 years with good care.
• Temperament
  Peaceful, schooling.
• Temperature
  23 to 28°C, 73 to 82°F
• pH
  6.0 to 8.0, commonly kept around 6.0 to 7.5 for display.
• Group size
  At least 6, larger groups look better and act more naturally.
• Tank focus
  Long footprint, open swimming space, shaded edges with plants and wood.
• Best visual trick
  Softer light and a darker substrate to highlight iridescence.

Tropical Fish Co. Notes

Congo Tetras are a classic for a very good reason. They are genuinely stunning fish, even for people who think they have seen it all. In a healthy group you get that shifting oil slick shimmer, blues, golds, reds, and violet flashes that change every time they turn.

Unlike a lot of pretty fish that only shine in photos, Congo Tetras put on a live performance all day. They cruise, they spar gently, they show off, and the males carry those flowing fins like they know they are the centerpiece.

They are also a perfect reminder that schooling fish should be kept as a real group. Two or three can look timid and washed out. A proper group relaxes, spreads out, and the color turns on, especially when the lighting is slightly soft and the diet includes a rotating mix of quality foods.

If you want the full classic Congo look, give them swimming length, keep water quality stable, and do not overbrighten the tank. Do that, and you get a fish that earns its reputation every single time you walk past.