Can Clown Killifish and Goldfish (Comet / Common) Live Together?

Clown Killifish is a peaceful species (2/10), while Goldfish (Comet / Common) is peaceful (1/10). This modest difference means Clown Killifish may occasionally assert dominance over Goldfish (Comet / Common).

Clown Killifish and Goldfish (Comet / Common) both frequent the Top (Surface) 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: Clown Killifish is a known jumper, so a tight-fitting lid is essential.

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. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 5–8 dGH. Regular testing will ensure conditions stay within this range. An aquarium test kit is recommended for monitoring.

To house Clown Killifish and Goldfish (Comet / Common) together, plan for an aquarium of at least 240 litres with a minimum length of 120 cm. This accounts for the larger species' space requirements with an additional 20 % buffer to reduce territorial tension.

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: Plants - Floating, Plants - Densely covered, Leaf Litter/Blackwater, Sand (Sifters), Smooth Gravel (Sensitive Barbels). Meeting these requirements will help both species thrive.

Note a potential conflict in setup requirements: Goldfish (Comet / Common) is a plant destroyer, which conflicts with Clown Killifish's requirement for live plants. Compromise where possible or prioritise the more critical need.

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 Clown Killifish 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 Clown Killifish receives an adequate share.