Can Japanese Ricefish (Medaka) and Tanganyikan Clown Cichlid (Eretmodus) Live Together?

Japanese Ricefish (Medaka) is a peaceful species (2/10), while Tanganyikan Clown Cichlid (Eretmodus) is semi-aggressive (7/10). This notable difference means Tanganyikan Clown Cichlid (Eretmodus) may occasionally assert dominance over Japanese Ricefish (Medaka).

In terms of spatial distribution, Japanese Ricefish (Medaka) prefers the Top (Surface) zone, whereas Tanganyikan Clown Cichlid (Eretmodus) occupies the Bottom (Substrate) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

Worth noting: Japanese Ricefish (Medaka) is a known jumper, so a tight-fitting lid is essential.

To improve the chances of a peaceful coexistence in this community tank: Provide a significantly larger tank (at least 50% more volume than the minimum) to allow both Japanese Ricefish (Medaka) and Tanganyikan Clown Cichlid (Eretmodus) to establish separate territories. Add plenty of line-of-sight breaks using driftwood, rocks, and dense planting to reduce territorial confrontations. 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 24°C and 28°C. Aim for the midpoint of this range (around 26.0°C) for optimal comfort.

Both fish can tolerate a pH between 8 and 8.5. Maintaining a stable value within this band is more important than hitting an exact number.

For general hardness, the shared comfort zone is 10–25 dGH. Regular testing will ensure conditions stay within this range.

To house Japanese Ricefish (Medaka) and Tanganyikan Clown Cichlid (Eretmodus) together, plan for an aquarium of at least 100 litres with a minimum length of 90 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: Plants - Densely covered, Plants - Floating, Smooth Gravel (Sensitive Barbels), Established Algae (Otocinclus). Meeting these requirements will help both species thrive.

Japanese Ricefish (Medaka) prefers Low (Still Water) flow while Tanganyikan Clown Cichlid (Eretmodus) needs High (River/Stream) flow. Consider positioning filter outlets and using baffles to create zones of different current intensity within the same tank.

This pairing usually fails when the tank is treated like a standard mixed community and the caution flags are ignored. Japanese Ricefish (Medaka) and Tanganyikan Clown Cichlid (Eretmodus) need extra room, more cover, and closer observation during the first few weeks so small aggression, feeding, or territory issues do not snowball into a long-term problem.