Not furry, but we like them anyway.
Medaka
Oryzias latipes
Also called Japanese rice fish, Japanese killifish
From Japan, where it lives in rice paddies, ponds, marshes and slow streams of Honshu, Shikoku and Kyushu. Older sources include wider East Asian populations now often treated as separate species.12
A friendly guide, not veterinary advice. For anything about your pet's health, ask your vet.
At a glance the quick version
Looks how to spot one
Small, slender scaled fish
A small, slim fish with a flat back, upturned mouth and large eyes. Males have longer rays in the dorsal and anal fins than females, which helps tell the sexes apart.23
Personality what they are like
A peaceful, gentle fish that lives in schools and can even recognise individual tankmates by their faces.23
Daily activity how busy a day looks
An active surface-swimming fish that does best in a group with open water near the top.13
Grooming and care the hands-on bits
Easy to maintain. Prefers cooler water and usually needs no heater in a temperate room; keep similar-sized, peaceful companions.13
Home where they are happiest
Aquarium of at least about 45 x 30 cm (around 40 litres) or a pond or patio tub. Water about 16 to 24 °C (survives a far wider range), pH roughly 6.5 to 8.5, hardness 5 to 25 dGH.123
Food basics what goes in the bowl
Omnivore and micropredator. In nature it eats mosquito larvae and plankton; in captivity small live or frozen foods (daphnia, brine shrimp, chopped bloodworm) plus good flakes or granules.123
Company who they like around
The story where it all began
Medaka have been kept as pets in Japan since the 17th century, making them one of the oldest pet fish there. In the 20th century they also became an important laboratory animal thanks to their hardiness and short generation time.23
Fun facts for the dinner table
- 1
Medaka were the first vertebrates to mate in orbit, with healthy fry hatching aboard the Space Shuttle Columbia in 1994.2
- 2
Medaka can survive water temperatures from near freezing up to about 42 °C.2
- 3
Females carry their egg cluster for a while before attaching it to plants.1
- 4
Medaka was the first non-mammal vertebrate in which a sex-determining gene (DMY) was identified.2
Recognised by the official bits
- IUCN Red List
- Assessed as Least Concern (1 March 2018).1
- Fishkeeping
- Hundreds of commercial strains (around 456 cited) are bred for the hobby.2
- Science
- A long-established laboratory model organism.2
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Medaka. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- FeedingSmall amounts once or twice a dayevery day
- Temperature checkevery day
- Water changeAbout 25% of the waterevery week
- Water testevery week
- Glass cleanevery week
- Filter rinseRinse in old tank water, never tap waterevery month
Owner questions the things everyone asks
How often should I feed my Medaka?
Feed your Medaka small amounts once or twice a day. Furry Diary's starting plan suggests daily feeding in small portions.231 Furry Diary plan
What does a Medaka eat, and what should it never eat?
Medakas are omnivores and micropredators, enjoying small live or frozen foods like daphnia and brine shrimp, plus good flakes or granules. Never feed them anything that could harm them, but specific foods to avoid are not listed in the provided information.231
How much space does a Medaka need?
A Medaka needs an aquarium of at least about 45 x 30 cm (around 40 litres), or a pond or patio tub. This gives them room to swim actively near the surface.231
What temperature, light or water does a Medaka need?
Medakas prefer cooler water, ideally 16 to 24 °C, with a pH of 6.5 to 8.5 and hardness of 5 to 25 dGH. They usually need no heater in a temperate room, and Furry Diary's plan includes daily temperature checks.231 Furry Diary plan
How often should I clean a Medaka's home?
Furry Diary's plan suggests a weekly 25% water change, weekly water testing and glass cleaning, and a monthly filter rinse using old tank water. This keeps their home healthy. Furry Diary plan
Can a Medaka live with others?
Yes, Medakas are peaceful schooling fish that do best in groups of eight or more. They can even recognise individual tankmates by their faces.23
How long does a Medaka live?
Medakas typically live between 2 and 5 years. With good care, they can enjoy a full lifespan.2
Can I handle a Medaka?
It's best not to handle Medakas as they are small, delicate fish. They are active swimmers that thrive in their aquatic home.
Written from the sources on this page, a few checked guides (VCA, ASPCA, RSPCA) and Furry Diary's own starting care plan. A friendly guide, not a vet's advice.
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Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at support@furrydiary.app and we will fix it.
- FishBase: Oryzias latipes fishbase.seused for range, size, temperature, pH, hardness, habitat, diet, IUCN, egg carrying
- Wikipedia: Japanese rice fish en.wikipedia.orgused for range, size, lifespan, colours, history, research, space flight, schooling
- Seriously Fish: Oryzias latipes seriouslyfish.comused for tank size, water parameters, diet, group size, sexing, colour forms
- VCA Animal Hospitals: Feeding times and frequency for your dog vcahospitals.comused for owner questions
- ASPCA: Dog grooming tips aspca.orgused for owner questions
- ASPCA: Cat grooming tips aspca.orgused for owner questions
- ASPCA: People foods to avoid feeding your pets aspca.orgused for owner questions
- RSPCA: What to feed your rabbit rspca.org.ukused for owner questions
Checked 2026-09-30. Text is written in our own words from these sources.