Medaka Rice Fish Care Guide

Medaka Rice Fish Care Guide: Everything You Need to Know

Medaka (Oryzias latipes) are one of the hardiest, most rewarding fish I keep. I breed all my medaka outdoors here in QLD, and they have become one of the most popular species I sell. If you are thinking about keeping medaka, this guide covers everything you need to get started.

What are medaka?

Medaka are small freshwater rice fish originally from Japan, where they have been kept and selectively bred for hundreds of years. They are peaceful, social fish that do well in nano tanks, indoor aquariums, outdoor tubs, and ponds. At adult size they reach about 3.5cm, which makes them perfect for smaller setups.

What makes medaka special is the sheer variety of colours and patterns available. From classic orange himedaka to metallic Miyuki blues, red and white kouhaku, tricolour, stardust varieties, and more. There is a medaka for every taste.

Tank and setup requirements

Medaka are not fussy about their setup. Here is what they need:

• Tank size: 20 litres minimum for a small group, but bigger is always better. They are active swimmers and appreciate some space.
• Temperature: 16 to 22 degrees Celsius is ideal, but they tolerate an incredible range from 3 to 42 degrees Celsius. This is what makes them so well suited to outdoor keeping in Australia. No heater needed.
• Filtration: A gentle sponge filter is perfect. They do not like strong flow, especially near the surface where they spend most of their time.
• Substrate: Sand or fine gravel works well. They are not bottom dwellers so substrate choice is more about aesthetics.
• Plants: Medaka thrive in planted setups. Floating plants like guppy grass, red root floaters, and floating bamboo are especially good because medaka lay their eggs on floating plant roots.
• Lighting: Natural sunlight is best if keeping them outdoors. For indoor tanks, standard aquarium lighting is fine.

Keeping medaka outdoors

This is where medaka really shine, and it is how I breed mine. A simple outdoor tub or half wine barrel with some floating plants, a few botanicals, and natural sunlight is all you need.

In Australia, medaka do well outdoors year-round in most areas. They handle the heat of a QLD summer and can survive cold winter nights as long as the water volume is large enough to prevent rapid temperature swings. Larger tubs are more stable than small containers, so aim for at least 40 litres for an outdoor setup.

I breed my medaka outdoors following the natural seasons. They breed most actively in the warmer months when daylight hours are longer. As autumn arrives they slow down, and through winter they mostly rest. After a decade of keeping high volume Medaka, I am convinced this seasonal cycle actually produces healthier, tougher fish compared to breeding under artificial conditions year-round.

What to feed medaka

Medaka are not picky eaters. They will accept:

A quality small pellet or flake food as their daily staple. I like the DRP range.

Live food is excellent for conditioning and colour. Daphnia, baby brine shrimp, and microworms are all great options.

Outdoor medaka will also graze on algae, biofilm, and tiny insects that land on the water surface. This natural feeding is one of the benefits of outdoor keeping, you still do need to supplement feeding to ensure they have enough. 

Feed once or twice a day, only as much as they can eat in a couple of minutes.

Breeding medaka

One of the best things about medaka is how easy they are to breed. A well-fed group in the right conditions will breed without any special effort from you. They will breed in the spring and summer months. 

Females carry fertilised eggs attached to their belly for several hours before depositing them on floating plant roots or spawning mops. The eggs are relatively large and easy to spot.

If you want to raise the fry, collect the eggs and move them to a separate container. They hatch in about 10 to 14 days depending on temperature. Newly hatched fry are small but can eat paramecium or vinegar eels as a first food, then graduate to microworms and baby brine shrimp as they grow.

If you leave the eggs with the adults, some fry will survive in a well-planted setup, but the adults will eat some of them. Separating the eggs gives you a much higher survival rate.

Tankmates

Medaka are peaceful and do well with other gentle species. Good tankmates include:

• Cherry shrimp (medaka will not bother adult shrimp, though they may eat baby shrimplets)
• Ramshorn snails for algae control
• Other peaceful nano fish of a similar size

Avoid keeping them with anything large or aggressive that might see them as food.

Common varieties

I breed a wide range of medaka varieties including Miyuki (metallic blue), Tiger (striped), Kouhaku (red and white), Platinum, Black, Galaxy, Stardust, and many more. Each variety has been selectively bred for specific colours and patterns, but they all share the same hardy, easy-to-keep nature.

Browse all my medaka varieties

Why I keep medaka

Medaka are one of my favourite species in my 155-tank fish room. They are hardy enough to handle Australian conditions outdoors, they breed readily, and the variety of colours available is incredible. Whether you keep them in a nano tank on your desk or a tub in your backyard, they are endlessly rewarding.

If you have any questions about keeping medaka, just email me at elyza@handpickedaquatics.com 

Cheers,

Elyza

Hand Picked Aquatics