Rainbow Platy (Xiphophorus variatus)

Discover the Rainbow Platy, a variatus platy in yellow, blue and red

The Rainbow Platy is a colour form of the variatus platy, Xiphophorus variatus, bred for aquariums from a small livebearer of eastern Mexico. Our photographs show a golden yellow fish whose flank scales are edged with a blue-green iridescence, so the body flashes from yellow to turquoise as it turns. A small blue patch sits on the gill cover, the dorsal fin is yellow with dark spots, and the tail and anal fin glow orange-red. Yellow, blue-green and red on one small fish: that is the rainbow.

The variatus platy is one of the most adaptable fish in the livebearer range. It is hardy, peaceful and easy to feed, it thrives in the moderately hard to hard water common across the UK, and it tolerates cooler indoor water than most tropical community fish. OATA includes it among the species suitable for an unheated indoor aquarium.

Sort out the names

See how it compares with our other variatus platies

Seriously Fish notes that wild variatus platies are slimmer than common platies with a slightly longer dorsal fin, and that breeders have crossed the species with swordtails and common platies to create many of the forms on sale. Within our range, the Sunset Variatus Platy warms from yellow to orange-red without the blue-green sheen, the Orange Gold Variatus Platy is a warm orange fish, and the Hawaii Variatus Platy is another named line. If you would rather have a mix, the Assorted Variatus Platy brings several colours together. All share the care described here and will interbreed.

Understand what you are buying

Each purchase brings one live Rainbow Platy of medium size, a youngster that will grow a little more. We cannot choose or guarantee sex. Males are smaller and carry the gonopodium, a pointed anal fin used for mating; females are larger and fuller-bodied with a rounded, fan-shaped anal fin. The amount of blue-green sheen and the depth of the red tail vary from fish to fish, and colours are often muted for a few days after delivery.

Choose a group size

• Three fish: the smallest group OATA suggests, ideally one male and two females.
• Six fish: a lively display at the same two-to-one ratio.
• All one sex: OATA's unheated-aquarium guidance mentions single-sex groups as a way to avoid unwanted male attention, and it also avoids fry.

Please read our delivery and Live Arrival Guarantee page before ordering, and have your aquarium fully cycled.

Give the rainbow platy room to swim

OATA gives the variatus platy an adult size of 6–8 cm in both its platy and its unheated-aquarium care sheets. FishBase records a maximum of 7.0 cm total length, and Seriously Fish gives 50 mm standard length, measured without the tail. Females outgrow males.

For a small group, OATA's minimum is 45 litres. Seriously Fish recommends a base of 60 × 30 cm, about 54 litres, and FishBase gives a minimum aquarium length of 60 cm. A 60 cm tank is a practical starting point, and our article on fish for a 60-litre tank shows what else fits alongside.

Plan the stocking

1. Base: at least 60 × 30 cm.
2. Adults: plan for fish of 6–8 cm.
3. Growth in numbers: Seriously Fish reports broods of over 100, so check your plans in our stocking calculator before the first fry appear.

Recreate a weedy, sunlit backwater

In the wild, Seriously Fish describes shallow, heavily vegetated streams, ponds, swamps, canals and ditches, often rich in algae and phytoplankton, and FishBase adds warm springs and weedy canals. That points to a tank with plenty of plants, gentle flow, good light and a little algae left to graze.

Arrange the aquarium

A lid is sensible for any platy tank; OATA calls it optional but advisable. Our variatus platy guide has more layout ideas for this species.

Set hard water at a moderate temperature

The variatus platy needs alkaline, mineral-rich water but is relaxed about temperature. The sources agree on pH, overlap on temperature and differ on hardness.

Line up the water values

Decide whether you need a heater

OATA's unheated-aquarium care sheet lists the variatus platy at 17–27°C and stresses that such fish may only be kept indoors, never outside. In a living room that stays warm all year, the tank may hold within range without a heater. In a cold room, a conservatory or a house that cools sharply at night, fit a heater set at about 22°C so the water stays inside every source's range. Compare your tap water in our water matcher; soft, acidic water does not suit this species.

Filter for a growing population

Seriously Fish suggests a filter turning the water over four to five times an hour, roughly 215–270 litres per hour for a 54-litre tank, and a heater of about 50 W for a room near 20°C. Because broods can be large, size the filter for the population you expect in three months, not the fish you start with.

Keep to a weekly plan

1. Test ammonia, nitrite, nitrate, pH and hardness each week, as OATA advises.
2. Change 25% of the water with dechlorinated water at the same temperature.
3. Siphon the gravel and remove decaying leaves.
4. Rinse sponges only in tank water taken out during the change.
5. Count young fish and rehome surplus before the tank becomes crowded.

Feed a greens-first diet

Seriously Fish describes the variatus platy as an omnivore that eats small bottom-living invertebrates and detritus in the wild, and FishBase lists worms, crustaceans, insects and plant matter. In the aquarium it takes frozen, live and dried foods readily. OATA's guidance is one feed a day of a quality flake or granule with a high algae content, only as much as is eaten within a few minutes, with occasional live or frozen food.

Measure out each meal

• Daily: algae or spirulina-based flake, crushed for medium-sized fish.
• Twice or three times weekly: Daphnia, brine shrimp or bloodworm instead of part of the flake.
• Cooler tanks: fish eat less at the lower end of the temperature range, so reduce portions and watch for leftovers.
• Fry: powdered flake or brine shrimp nauplii two or three times a day, as Seriously Fish suggests.

Acclimatise and settle the new fish

Before the fish arrive, check that ammonia and nitrite are zero, pH is 7.0–8.0 and the temperature is steady. OATA's method: lights off, float the sealed bag for around 10 minutes, add small amounts of tank water over up to 20 minutes, then release the fish and discard the bag water. Our acclimatisation guide covers each step in detail.

Watch the first week

Build a peaceful community around it

Seriously Fish calls the variatus platy peaceful, hardy and a good community fish, while warning that males can be relentless in their attention to females. OATA recommends at least three fish with two females for each male. Choose companions that like the same hard water and will not outcompete platies at feeding time; in a cooler tank, pick fish that share the lower temperatures too.

Pick compatible companions

Test a planned mix in our tank mates tool. Browse more platy fish for sale and livebearers, the platy category and our full variatus platy range. The platy care guide covers both platy species side by side.

Manage large broods

Variatus platies are prolific. Seriously Fish gives a gestation of around 4–7 weeks and says broods of over 100 fry are not uncommon; FishBase gives about 24 days and up to 100 young; OATA's platy and swordtail sheet gives 24–30 days and 20–80 fry. The figures differ, but every source agrees that a healthy female can produce a big brood regularly.

Choose a breeding plan

1. Natural: dense plants let a few fry survive in the main tank.
2. Planned: Seriously Fish suggests moving a heavily pregnant female to a separate tank to give birth and returning her afterwards.
3. Rearing: two or three small meals a day; fry grow quickly.
4. Limiting: a single-sex group avoids breeding entirely.

Breed Rainbow to Rainbow to keep the look. Seriously Fish also asks keepers not to cross wild-type variatus with domestic forms.

Recognise health problems early

Seriously Fish notes that most variatus platies on sale are mass-produced and that many commercially bred platies are not very hardy because of inbreeding. OATA's warning signs are clamped fins, flicking or shaking, hanging at the surface or sitting on the bottom, colour darker or paler than usual, white spots or fluffy growths, lost fins or scales, changed breathing and loss of appetite.

Act on what you see

FishBase lists the variatus platy as a potential pest outside its range, and Seriously Fish records feral populations in countries including the USA, Costa Rica, Colombia, Singapore and Hong Kong. OATA notes that species on its unheated list may not legally be kept outdoors. Never release this fish or put it in a garden pond; return unwanted fish to a shop or another keeper.

Answer Rainbow Platy buying questions

What is a Rainbow Platy?

It is an aquarium-bred colour form of the variatus or variable platy, Xiphophorus variatus, a small livebearer from the Atlantic slope of Mexico. Our photographs show a golden yellow body with blue-green iridescent scale edges along the flank, a small blue patch on the gill cover, a yellow dorsal fin with dark spots and an orange-red tail and anal fin. The mix of yellow, blue-green and red is where the "rainbow" name comes from.

Is a Rainbow Platy the same as a common platy?

No. It belongs to a different species, Xiphophorus variatus, which Seriously Fish describes as slimmer in the wild than the common platy, X. maculatus, with a slightly longer dorsal fin. The two need very similar care, and breeders have crossed them, so many shop fish carry genes from both.

How is it different from a Hawaii or Sunset Variatus Platy?

They are the same species with the same care. Our Sunset Variatus Platy shades from yellow to orange-red without the blue-green sheen, and the Hawaii Variatus Platy is a differently patterned line. The Rainbow on our photographs combines a yellow body, iridescent blue-green scales and a red tail.

Can a Rainbow Platy live in an unheated tank?

Indoors, often yes. OATA lists the variatus platy among fish for unheated indoor aquariums at 17–27°C and FishBase gives 15–25°C. OATA also says these fish must not be kept outdoors. In a cold room, a heater set at about 22°C keeps the water within every source.

How big does it grow?

OATA gives 6–8 cm. Seriously Fish gives a maximum of 50 mm standard length, without the tail, and FishBase records 7.0 cm total length. Females grow larger than males.

What tank and water does it need?

At least 45 litres (OATA), ideally a 60 × 30 cm base of about 54 litres (Seriously Fish). Keep it in hard, alkaline water at pH 7.0–8.0; Seriously Fish gives 14–30 dGH and FishBase 9–19, so aim for about 14–19.

How many should I buy?

At least three, with two females for each male, as OATA advises. Seriously Fish warns that males can be relentless in their attention to females.

How many babies will it have?

Seriously Fish says broods of over 100 fry are not uncommon after a gestation of around 4–7 weeks. FishBase gives about 24 days and up to 100 young. Either way, a mixed group grows quickly.

How many fish come with one purchase?

One live fish of medium size. Sex is not chosen or guaranteed, and colour varies slightly between fish.

Check the sources behind this guide

• Seriously Fish: Xiphophorus variatus — maximum size, aquarium base, water values, natural habitat, diet, behaviour, gestation, brood size, hybrid strains and feral populations of the variatus platy.
• FishBase: Xiphophorus variatus — maximum recorded length, subtropical temperature range, pH and hardness, distribution, habitat, gestation, brood size, minimum aquarium length and pest status.
• OATA: How to look after swordtails & platies — UK trade-body guidance for platies and swordtails: adult sizes, tank volumes, water values, group size and sex ratio, feeding, acclimatisation, maintenance, breeding and health signs.
• OATA: How to pick and look after fish for an unheated aquarium — UK trade-body guidance listing the variatus platy (6–8 cm, 17–27°C, indoors only) and the white cloud mountain minnow among fish for unheated indoor aquariums.
• Tropical Fish Co delivery policy — current dispatch days and Live Arrival Guarantee terms.