Red Stardust Ricefish (Oryzias latipes 'Red Stardust')

Choose a glittering red ricefish for a cool aquarium

The Red Stardust Ricefish is an ornamental strain of the medaka or Japanese rice fish, Oryzias latipes, bred for colour and sparkle. Our fish shows a slender orange-red body sprinkled with glittering gold and silver scales, a large silvery eye and clear fins edged in orange. If you want a small, peaceful, easy-to-breed fish for a cool indoor aquarium, a group of Red Stardust Ricefish is a lively, eye-catching choice.

Red Stardust is a trade name rather than a formal standard, so expect variation. Aquarium Glaser describes sparkled medaka as fish with scattered, striking silver-white shiny scales and notes that colour intensity differs considerably between individuals, which is why breeders keep selecting for stronger colour. The species itself is famous well beyond fishkeeping: Seriously Fish notes that medaka have been used in biology for more than a century and were the first vertebrates to mate in space, in the mid-1990s.

Decide from the complete care picture

Identify the medaka and the Red Stardust strain

Medaka, Japanese rice fish and ricefish are all names for Oryzias latipes. Ricefish are often sold alongside killifish, but they belong to their own family, Adrianichthyidae, in the same order as halfbeaks and needlefish. Seriously Fish gives the wild range as Japan, South Korea, Taiwan, eastern China including Hainan and Hong Kong, Laos and Vietnam, and lists habitats from coastal brackish waters and tidal mangroves to forest streams, rice paddies, canals, pools and oxbow lakes. FishBase adds ponds, marshes and small lowland streams, mostly with slow-moving water, and notes a wide tolerance of salinity.

Seriously Fish notes that the golden ornamental form is now seen more often than the natural one. Red Stardust is one of many strains bred since, combining red-orange colour with sparkling scales. Compare it with our Tomoki Medaka Ricefish, a paler strain of the same species, or see our full range of killifish and ricefish.

Tell males from females

Know exactly what you receive

One purchase supplies one live Red Stardust Ricefish. Sex is not chosen or guaranteed. The photographs show the strain, not the individual you will receive: the depth of red and the amount of glitter vary from fish to fish, as Aquarium Glaser describes for sparkled strains.

Plan the group before you order

• Group size: Seriously Fish says medaka look and behave most confidently in a group of eight or more.
• Keep the strain pure: Tomoki and other medaka strains are the same species and will interbreed. Keep them in separate aquariums if you want Red Stardust fry to stay true.
• Buy together: starting the group in one order helps the fish settle.

Keep it indoors: ponds and patio tubs

Medaka tolerate cool water, and Aquarium Glaser notes that in mild climates they are even kept in garden ponds, so some sellers suggest patio tubs. In England and Wales that is not allowed. OATA explains that only six kinds of fish, including goldfish, koi and orfe, may be kept in garden ponds, and that every other freshwater fish, temperate species included, must be kept only in an indoor aquarium. OATA's guide to unheated aquariums repeats that cool-water aquarium fish are not legally permitted outdoors, and the government's non-native fish guidance links to a checklist that lists Oryzias for indoor aquaria only. If you live in Scotland or Northern Ireland, check your local rules before keeping any fish outdoors.

The reason is simple: Seriously Fish records medaka introduced into the wild in the USA, Cuba, Kazakhstan, Turkmenistan, Iran and Russia. Never release aquarium fish.

Plan a small, cool aquarium

Seriously Fish gives a maximum of 36 mm standard length (measured without the tail) and FishBase 4.0 cm, so adults stay around 3.5–4 cm. For a group, Seriously Fish recommends an aquarium with a base of at least 45 × 30 cm, about 41 litres. OATA adds that it is worth buying the largest aquarium you reasonably can, because bigger tanks keep temperature and water quality more stable. Browse our nano tank fish for other small species.

Use a three-step space check

1. Measure the base: at least 45 × 30 cm.
2. Count the group: eight or more ricefish, plus any companions at adult size. Our stocking calculator helps you check.
3. Check the spot: indoors, away from radiators, draughts and direct sunlight, as OATA advises.

Arrange fine-leaved plants and calm water

Ricefish come from ponds, marshes, rice paddies and slow streams, as FishBase describes. Seriously Fish describes females attaching their eggs to fine-leaved plants or spawning mops, and notes that dense planting lets some fry survive in a community aquarium.

Divide the aquarium by function

Set water values for a cool-water fish

Medaka are not tropical fish. Seriously Fish gives 16–22°C, pH 6.5–8.5 and 5–25 dGH, warns that permanent exposure to warm conditions is likely to shorten their life, and notes that many homes can keep them without year-round heating. FishBase gives 18–24°C, pH 7.0–8.0 and a hardness of 9–19 dH. The table shows the range that satisfies both.

Separate habitat values from waste readings

UK tap water varies a lot from area to area, so check your water company's report for your postcode and compare it with the range using our water matcher. Treat every water change with a tap water conditioner. If the room stays within 18–22°C, you may not need a heater at all; if it falls lower in winter, a heater set inside the range keeps things steady. Do not keep ricefish permanently in a warm tropical aquarium. Our water chemistry guide explains each test.

Filter gently and change water every week

OATA's guide to unheated aquariums says a filter is essential whatever the size of the tank. Choose a gentle filter, such as a small sponge filter, so the fish are not blown around and eggs and fry are not sucked in.

Follow a weekly maintenance sequence

1. Test ammonia, nitrite, nitrate and pH at least once a week, as OATA advises.
2. Change about 25% of the water, siphoning waste from the substrate.
3. Use conditioned water at the same temperature.
4. Rinse filter media in the water you removed, never under the tap.
5. Look for eggs on the plants and move them if you want to raise fry.

Feed tiny meals every day

Seriously Fish describes medaka as micropredators of small insects, worms, crustaceans and zooplankton, and FishBase calls them omnivorous. In the aquarium, Seriously Fish recommends small live or frozen foods every day, such as daphnia, brine shrimp (artemia) and chopped bloodworm, alongside suitably small flakes or granules. OATA's advice is to feed only what the fish eat within a few minutes, because leftovers foul the water.

Build one measured meal

Introduce the group to a mature aquarium

OATA warns that adding fish too quickly, or to a new aquarium, can cause new tank syndrome, with harmful ammonia and nitrite. Make sure the filter is fully established first; our nitrogen cycle guide explains how to check. Then follow OATA's floating-bag method: lights off, float the sealed bag for about 10 minutes to match the temperature, add small amounts of aquarium water to the bag over up to 20 minutes, and net the fish across with as little bag water as possible. Our guide on how to acclimatise new fish has more detail.

Use a first-week checkpoint plan

Choose small, peaceful, cool-water companions

Seriously Fish describes medaka as generally peaceful and mostly non-aggressive towards each other. It suggests small companions such as some halfbeaks (Dermogenys), blue-eyes (Pseudomugil), bumblebee gobies (Brachygobius) and neritid snails, and advises against keeping other Oryzias species because they can hybridise. Whatever you choose, check that its temperature range overlaps 18–22°C; many small fish sold as companions prefer a warmer tropical aquarium.

Screen every tank mate

Read our White Cloud Mountain Minnow guide and check any mix in our tank mates tool before you buy.

Watch for health problems and act early

OATA describes healthy fish as having clear, bright eyes, undamaged fins, intact scales and steady swimming. Warning signs include clamped fins, flicking against objects, shimmying and changes in feeding or behaviour.

Pair each observation with an action

Breed Red Stardust Ricefish at home

Seriously Fish calls medaka quite easy to breed and fairly prolific. A well-conditioned female can spawn every few days, or even daily, usually early in the morning; FishBase explains that the eggs mature overnight and are released at dawn. Females carry the sticky eggs hanging from their belly for a while before attaching them, singly or in small clumps, to fine-leaved plants or spawning mops. Incubation takes one to three weeks, depending on temperature.

The adults ignore the eggs but will eat free-swimming fry, so move eggs to a separate container or keep the aquarium densely planted. Seriously Fish suggests raising the fry on microworm, such as our live microworms, or newly hatched brine shrimp, and separating young of different sizes, because larger fry eat smaller ones. FishBase estimates a generation time of about 0.3 years, so a well-kept group can grow quickly. To keep the Red Stardust look, breed from your brightest fish and keep the strain apart from other medaka.

Browse our full range of killifish, read our killifish buying guide, and before you order, see our delivery and Live Arrival Guarantee information.

Answer Red Stardust Ricefish buying questions

What is a Red Stardust Ricefish?

It is an ornamental colour strain of the Japanese rice fish or medaka, Oryzias latipes, with an orange-red body sprinkled with glittering scales. Red Stardust is a trade name rather than a formal standard, so the depth of red and the amount of sparkle vary from fish to fish.

Is a ricefish the same as a medaka?

Yes. Medaka, Japanese rice fish and ricefish are all names for Oryzias latipes. The Red Stardust is one of many colour strains of the same species.

Can I keep Red Stardust Ricefish in a pond or patio tub?

Not in England and Wales. OATA explains that only six kinds of fish, such as goldfish and koi, may be kept in garden ponds there, and that every other freshwater fish must be kept in an indoor aquarium. The government checklist lists Oryzias for indoor aquaria only, even though medaka are kept outdoors in some other countries.

Do ricefish need a heater?

Often not. Seriously Fish gives 16–22°C and says many homes can keep medaka without year-round heating, warning that permanently warm water is likely to shorten their life. Aim for 18–22°C, where Seriously Fish and FishBase overlap, and use a heater only if the room gets colder than that.

How big do Red Stardust Ricefish grow?

Small: Seriously Fish gives 36 mm standard length and FishBase 4.0 cm, so expect adults of around 3.5–4 cm.

How many ricefish should I keep?

Seriously Fish says medaka look and behave most confidently in a group of eight or more, in an aquarium with a base of at least 45 × 30 cm.

Can I keep them with Tomoki Medaka or other medaka?

They will live together peacefully, but they are the same species and will interbreed, so keep strains apart if you want Red Stardust fry to stay true. Seriously Fish advises against mixing different Oryzias species because they can hybridise.

How many fish come with one purchase?

One live Red Stardust Ricefish. Sex is not chosen, and the glitter and colour vary between fish. Order eight or more for a group.

Consult the care references

• Seriously Fish: Oryzias latipes — size, aquarium base, water range and warm-water warning, diet, companions, sexing, breeding and the species' role in science.
• FishBase: Oryzias latipes — maximum length, temperature and water range, habitat, diet and reproduction.
• Aquarium Glaser: Oryzias latipes and 'Sparkled Orange' — adult size, keeping in mild climates abroad, and the sparkled-scale strains.
• OATA: How to pick and look after fish for an unheated aquarium — UK guidance on cool-water aquariums, water quality, feeding, acclimatisation and the indoor-only rule.
• OATA: Can I keep tropical freshwater fish in an outside pond? — which fish may be kept in garden ponds in England and Wales.
• GOV.UK: Introduce or keep non-native fish and its ornamental fish checklist (13 October 2026) — the indoor-aquarium general licence that covers Oryzias.
• Tropical Fish Co delivery policy — current dispatch days and Live Arrival Guarantee terms.