Can Chao Phraya Giant Catfish (Paroon Shark) and Japanese Ricefish (Medaka) Live Together?

Chao Phraya Giant Catfish (Paroon Shark) is a semi-aggressive species (8/10), while Japanese Ricefish (Medaka) is peaceful (2/10). This notable difference means Chao Phraya Giant Catfish (Paroon Shark) may occasionally assert dominance over Japanese Ricefish (Medaka).

Large aggression gap (6 points) between Chao Phraya Giant Catfish (Paroon Shark) and Japanese Ricefish (Medaka) increases stress risk for the more peaceful fish.

In terms of spatial distribution, Chao Phraya Giant Catfish (Paroon Shark) prefers the Middle (Open Water) and Bottom (Substrate) zones, whereas Japanese Ricefish (Medaka) occupies the Top (Surface) zone. Because they use different levels of the water column, territorial disputes are less likely and the tank will appear more balanced.

There is a critical concern: the Piscivore (Eats small/nano fish) behaviour of one fish directly conflicts with the Nano / Bite-sized (Predation Risk) trait of the other — piscivorous fish will prey on nano-sized tank mates..

Worth noting: Chao Phraya Giant Catfish (Paroon Shark) is a known jumper, so a tight-fitting lid is essential.

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 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 Chao Phraya Giant Catfish (Paroon Shark) and Japanese Ricefish (Medaka) together, plan for an aquarium of at least 15000 litres with a minimum length of 600 cm. This recommendation combines the stricter species minimums with a community-load allowance so the pairing has realistic long-term space and filtration headroom.

Providing a mix of open swimming space and sheltered areas with rocks, driftwood, or plants will keep both species comfortable and allow natural behaviour.

Specific environmental needs for this combination include: Smooth Gravel (Sensitive Barbels), Plants - Densely covered, Plants - Floating. Meeting these requirements will help both species thrive.

Chao Phraya Giant Catfish (Paroon Shark) prefers High (River/Stream) flow while Japanese Ricefish (Medaka) needs Low (Still Water) flow. Consider positioning filter outlets and using baffles to create zones of different current intensity within the same tank.

Chao Phraya Giant Catfish (Paroon Shark) and Japanese Ricefish (Medaka) are the kind of pair that can look acceptable in a shop but become a maintenance problem at home. The main risk is not a single number in the chart; it is the way incompatible behavior, water needs, or pressure on space compounds over time once both fish are established in the same tank.