Can African Knifefish and Goldfish (Comet / Common) Live Together?

African Knifefish is a moderately assertive species (5/10), while Goldfish (Comet / Common) is peaceful (1/10). This notable difference means African Knifefish may occasionally assert dominance over Goldfish (Comet / Common).

African Knifefish and Goldfish (Comet / Common) both frequent the Middle (Open Water) and Bottom (Substrate) region of the setup. This overlap can increase competition for space, so providing ample room and cover is important to keep both species comfortable.

Additional behavioural considerations to keep in mind: Hyperactive swimmers can stress shy, slow-moving species through constant motion. Aggressive eaters may outcompete shy fish for food, leading to malnutrition.

Worth noting: African Knifefish is nocturnal and will be most active after lights-out, naturally reducing daytime encounters.

To improve the chances of a peaceful coexistence in this community tank: A larger aquarium with ample hiding spots can help diffuse aggression and give the less dominant fish space to retreat.

The safe temperature window for both species falls between 23°C and 24°C. Aim for the midpoint of this range (around 23.5°C) for optimal comfort.

Both fish can tolerate a pH between 6.5 and 7.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 5–15 dGH. Regular testing will ensure conditions stay within this range.

To house African Knifefish and Goldfish (Comet / Common) together, plan for an aquarium of at least 283 litres with a minimum length of 120 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Because this pairing requires extra vigilance, include plenty of hiding spots — caves, driftwood, and dense plant clusters — so the less dominant fish can retreat when needed.

Specific environmental needs for this combination include: Driftwood (Digestion/Hiding), Smooth Gravel (Sensitive Barbels), Plants - Floating, Sand (Sifters). Meeting these requirements will help both species thrive.

Both species do well with low (still water) water movement, so a standard filtration setup rated for the tank volume should suffice.

Feeding time deserves special attention with this pairing. Goldfish (Comet / Common) is an aggressive eater that may prevent African Knifefish from getting enough food.

Because Goldfish (Comet / Common) is a fast, competitive feeder, consider using sinking pellets or feeding at opposite ends of the setup to ensure African Knifefish receives an adequate share.