Medaka ricefish
Oryzias latipes
easy careOverview
The medaka ricefish (Oryzias latipes), or Japanese ricefish, is a small, hardy surface-dweller with an enormous following in Japan, where hundreds of colour strains — orange, white, blue, gold and metallic — are bred. It is peaceful, cool-tolerant and easy, equally at home in a planted indoor nano or an outdoor tub. Its upturned mouth and habit of cruising the top layer give a tank a lively, natural feel.
Tank & water
A shoal thrives in a planted 20-litre (5-gallon) tank or larger, and they especially enjoy a broad water surface. Length and surface area matter more than depth.
- Temperature: highly flexible, 15–28 °C; usually no heater is needed indoors, and they suit unheated tanks and mild-climate tubs.
- Water: neutral to hard and alkaline, pH 7.0–8.0, suits them best.
- Filtration: a gentle sponge filter keeps water clean without strong surface current.
- Planted: floating and fine-leaved plants give cover, shade and spawning sites.
Feeding
Medaka are omnivores that feed at the surface. A quality floating micro-pellet or flake is the staple, with small live and frozen foods — daphnia, cyclops, baby brine shrimp, mosquito larvae — which they relish and which bring out their colour. Feed small amounts once or twice a day; sinking food is often ignored.
Tankmates
Peaceful and small, medaka pair best with other calm, cool-tolerant species: White Cloud Mountain minnows, cherry shrimp, snails and small peaceful bottom-dwellers. Keep them in a group of their own kind for the best display, and avoid large or boisterous fish that will out-compete these gentle surface feeders.
Hardy, adaptable and full of colour strains to collect, the medaka ricefish is a rewarding, low-tech fish for a cycled indoor or outdoor setup.
Medaka ricefish — frequently asked questions
Do medaka ricefish need a heater?
No. Medaka are remarkably temperature-tolerant, thriving anywhere from about 15 to 28 °C, so they suit an unheated indoor tank and are popular for outdoor tubs and ponds in mild climates. Just avoid sudden swings and freezing conditions.
Can I keep medaka ricefish outdoors?
In mild climates, yes — they are a classic Japanese pond and tub fish, and colour up beautifully in natural light. Provide plants for cover and shade, protect them from extreme cold, and keep the water clean. Indoors, a planted nano suits them equally well.
Are medaka ricefish easy to breed?
Very. In good conditions females carry clusters of eggs at the vent and scatter them among fine plants or spawning mops. Remove eggs or adults to protect them, as the parents will eat both eggs and fry.
Found your model? Buy it at the right price.
UniverTrack tracks the real price of your aquarium gear across several retailers, spots fake discounts and warns you when it's genuinely the right moment to buy — with an AI assistant to guide you.