Can Asian Upside Down Catfish and Japanese Ricefish (Medaka) Live Together?
Asian Upside Down Catfish and Japanese Ricefish (Medaka) are not recommended as tank mates due to piscivorous fish will prey on nano-sized tank mates.. Housing these species together is likely to result in stress, health problems, or direct harm to one or both fish.
At a Glance
Can your tank handle Asian Upside Down Catfish and Japanese Ricefish (Medaka)?
Compatibility is only part of the answer. Test both fish with your real tank size, current stock, and maintenance needs to see if you have enough space and a safe stocking level before you add them.
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Behaviour & Temperament
Asian Upside Down Catfish is a semi-aggressive species (8/10), while Japanese Ricefish (Medaka) is peaceful (2/10). This notable difference means Asian Upside Down Catfish may occasionally assert dominance over Japanese Ricefish (Medaka).
Large aggression gap (6 points) between Asian Upside Down Catfish and Japanese Ricefish (Medaka) increases stress risk for the more peaceful fish.
In terms of spatial distribution, Asian Upside Down Catfish 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..
Additional behavioural considerations to keep in mind: Shrimp eaters may also prey on very small nano fish.
Worth noting: Asian Upside Down Catfish is nocturnal and will be most active after lights-out, naturally reducing daytime encounters. Also, Japanese Ricefish (Medaka) is a known jumper, so a tight-fitting lid is essential.
Water Parameters
The safe temperature window for both species falls between 23°C and 27°C. Aim for the midpoint of this range (around 25.0°C) for optimal comfort.
Both fish can tolerate a pH between 6.5 and 8. Maintaining a stable value within this band is more important than hitting an exact number.
For general hardness, the shared comfort zone is 5–20 dGH. Regular testing will ensure conditions stay within this range.
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Tank Setup
To house Asian Upside Down Catfish and Japanese Ricefish (Medaka) together, plan for an aquarium of at least 380 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.
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: Driftwood (Digestion/Hiding), Smooth Gravel (Sensitive Barbels), Plants - Densely covered, Plants - Floating. Meeting these requirements will help both species thrive.
Both species do well with moderate (standard) water movement, so a standard filtration setup rated for the tank volume should suffice.
Suitable Tank Sizes
Standard aquarium sizes large enough for both Asian Upside Down Catfish and Japanese Ricefish (Medaka).
Diet & Feeding
Feeding time deserves special attention with this pairing. Asian Upside Down Catfish is a known shrimp eater and may prey on small invertebrates or nano fish like Japanese Ricefish (Medaka).
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Frequently Asked Questions
Can Asian Upside Down Catfish and Japanese Ricefish (Medaka) live together?
No. This combination is not recommended. Key incompatibilities — such as critical behavioural conflicts — make cohabitation unsafe.
What size tank do Asian Upside Down Catfish and Japanese Ricefish (Medaka) need?
A minimum of 380 litres (tank length at least 120 cm) is recommended. This provides enough space for both species to establish their own areas and reduces the likelihood of territorial disputes.
What water temperature is best for Asian Upside Down Catfish and Japanese Ricefish (Medaka) together?
Keep the aquarium between 23°C and 27°C. A target of around 25.0°C sits comfortably within both species' preferred ranges.
Are Asian Upside Down Catfish or Japanese Ricefish (Medaka) aggressive?
Asian Upside Down Catfish is semi-aggressive (8/10) and Japanese Ricefish (Medaka) is peaceful (2/10). The gap in aggression levels means the calmer fish may experience stress from the more assertive one.
What pH do Asian Upside Down Catfish and Japanese Ricefish (Medaka) need?
Both species overlap in the 6.5–8 pH range. Consistency is key — avoid sudden swings, and test regularly to stay within this window.
How do I manage Asian Upside Down Catfish's territorial behaviour?
Provide line-of-sight breaks using rocks, driftwood, and dense planting. A larger tank gives Asian Upside Down Catfish space to claim a territory without encroaching on the other fish's area. Adding décor that divides the tank into distinct zones works especially well.
Does Asian Upside Down Catfish being nocturnal affect compatibility?
Asian Upside Down Catfish is most active after lights-out, which naturally reduces daytime encounters with its tank mate. This can actually be beneficial, as both fish get undisturbed time to feed and explore. Just ensure food reaches Asian Upside Down Catfish during evening hours.
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