Japanese Rice Fish (Medaka)
Oryzias latipes
The Japanese Rice Fish (Medaka) (Oryzias latipes) is a peaceful fish that's easy to keep. Give it a tank of at least 45 litres (12 US gallons), water held at 61-75°F, and a pH of 6.5-8.5. Always keep a group of at least 6 - they feel safest in numbers.
Captive lifespan reflects typical experience in a home aquarium, not maximum recorded age; genetics, sourcing, and care vary.
Natural distribution
Japan/Korea/China
- East & Southeast Asia
Regional colours match the stocking calculator's origin map.
Japanese Rice Fish (Medaka) Tank Setup
A tank of at least 45 litres (12 US gallons) works well. Keep the water at 61-75°F with a pH around 6.5-8.5, and set up both cover and open swimming space where they spend most of their time (Top/Mid). Always keep a group of at least 6 of their own kind - kept alone or in pairs they tend to turn shy, nippy, or wash out in colour.
What Do Japanese Rice Fish Eat?
They're not fussy eaters - feed a varied diet, rotating good-quality dry, frozen, and gel foods rather than the same thing every day, and match the food size to their mouths.
Japanese Rice Fish (Medaka) Tank Mates
Unheated tanks OK if room stays in range; great planted temperate setups The Japanese Rice Fish (Medaka) is peaceful, which is the first thing to weigh up when you choose tank mates. It's a shoaling fish, so settle a group of 6 or more of its own kind before adding anything else - a stressed, lonely fish is far more likely to nip or hide. Before you buy, run your full stocking list through our stocking calculator. It weighs temperament, adult size, and water needs together, which a single species page can't do on its own.
Are Japanese Rice Fish Good for Beginners?
Often recommended to beginners, but only after the tank is cycled and you can keep a proper school - not three fish in a new setup.
Japanese Rice Fish (Medaka) - frequently asked questions
What size tank do Japanese Rice Fish need?
Japanese Rice Fish need a tank of at least 45 litres (12 US gallons). A bigger tank is always easier to keep stable, and gives them more room to settle in and behave naturally.
How many Japanese Rice Fish should I keep together?
Keep a group of at least 6. Japanese Rice Fish are a shoaling species and become stressed, lose their colour, or hide when kept singly or in pairs.
What water parameters do Japanese Rice Fish need?
Keep them at 61-75°F with a pH of 6.5-8.5, steady rather than chased to an exact figure. In a cycled tank, ammonia and nitrite should both read 0 ppm, with nitrate kept low through regular water changes.
What do Japanese Rice Fish eat?
Japanese Rice Fish are omnivores and aren't fussy eaters. Feed a varied mix of good-quality dry, frozen, and gel foods, and match the food size to their mouths. Feed small amounts once or twice a day, and remove anything they don't eat.
Are Japanese Rice Fish good for beginners?
Yes - Japanese Rice Fish are a good beginner choice once the tank is fully cycled and you can keep a proper group. They are hardy but still need stable water and a school to feel secure.
Common mistakes with Japanese Rice Fish
- Buying fewer than 6 - Japanese Rice Fish (Medaka)s need a proper school to feel secure; isolated individuals hide, fail to colour up, or become stressed.
Building a community? Run the full list through the stocking calculator before you add anything else.
Great tank mates
Chosen from temperament, overlapping temperature/pH bands, plausible minimum tank footprints, and size versus yours in App-aquatic data. Hobby nuance always wins - verify stocking and temperament before purchasing.
Fish to avoid mixing with Japanese Rice Fish
These well-known species are commonly sold alongside this fish but are not recommended tank mates - verify before purchasing.
- OscarPredator - Oscar will eat or injure smaller tank mates
- AxolotlPredator - Axolotl will eat or injure smaller tank mates
- Betta (Male)Predator - Betta (Male) will eat or injure smaller tank mates
