Poeciliidae

Flag Platy

Xiphophorus maculatus

A form of:Common Platy

The Flag Platy, also known as the Sailfin Platy in English-speaking environments, stands out with its characteristic high dorsal fin. The first rays of this fin are noticeably thickened and taller than the subsequent ones, giving it a distinctive triangular shape, resembling a small flag or sail.

Tank
from 60 L (16 gal)
Temperature
20 – 28 °C (68 – 82 °F)
Size in aquarium
5 – 7 cm (2 – 2.8 in)
Acidity
pH 7–8.2
Natural rangeRange on the map
  • Belize
  • Fiji
  • Guatemala
  • Honduras
  • Mexico
  • Nicaragua

Tank conditions

Plan the tank stocking
Temperature
20 – 28 °C (68 – 82 °F)
Water pH
Neutral (7) – Slightly alkaline (8.2)
Water dH
Medium hardness (10) – Very hard (30)
Water salinity
no salt (freshwater)
Size in aquarium
5 – 7 cm (2 – 2.8 in)
Lifespan
4 years
Temperament
Peaceful (regular)
Toward small fish
not a predator
Required aquarium volume
from 60 L (16 gal)
Lighting
dimmed
Substrate
any (no restrictions)
Water flow
weak or moderate
Swimming level
near the surface
Feeding
Any (universal)
Keeping
Mixed solitary / pair / group
Jumping
noticeable a lid is needed
  • Lifespan. A lifespan to expect under good care, not a measured value: it depends heavily on tank volume, water quality and diet — and for selectively bred forms, on their origin as well.
  • Toward small fish. Based on the Predators category in the catalog or the temperament in the species parameters. “A risk to small fish” means the species is not a predator by habit, yet will swallow any fish that fits in its mouth.
  • Required aquarium volume. This is a husbandry recommendation, not a measured value: the volume depends on the keeping mode (mixed (solitary / pair / group)), footprint, decor and tank mates.

Care and keeping

Description

The Flag Platy is a selective breeding form distinguished by its characteristic high dorsal fin, which resembles a flag or a sail in shape. The fish's body is rhomboid, laterally compressed, with a relatively small head. Its coloration is extremely variable: red, yellow, golden, black, marbled, and other color morphs are found. Adult females are usually larger than males, reaching 5–7 cm in length. Males are smaller and easily distinguished by their gonopodium — a modified anal fin that serves as an organ of fertilization.

Habitat

In the wild, the original species inhabit water bodies in Central America, from Mexico to Nicaragua. They populate shallow areas of rivers, lakes, swamps, and flooded pastures with dense vegetation. Natural biotopes are characterized by both fresh and brackish waters, which explains the species' high adaptability to hard and alkaline water in aquarium conditions.

Behavior and Compatibility

Peaceful and active fish, suitable for community tanks. They prefer to stay in the middle and upper water layers. Intraspecific conflicts between males are possible but usually do not lead to serious injuries. To reduce stress levels, it is recommended to keep a group where the number of females predominates over the number of males. They get along well with other peaceful species of comparable size, such as guppies, swordtails, and smaller characins.

Care and Maintenance

Hardiness and unpretentiousness are characteristic features of platies, even their decorative varieties. For keeping 3–4 fish, an aquarium of 50–60 liters, equipped with several shelters, is quite sufficient. Optimal conditions include warm water (22–24°C) with a pH level close to neutral or slightly elevated. In terms of feeding, platies are undemanding and readily accept most common foods — both dry and frozen or live. Specialized platy foods offered by many well-known manufacturers are an excellent choice. Thanks to their ability to adapt to various keeping conditions and their peaceful nature, these fish can successfully coexist with most other non-aggressive species.

Diet

An omnivorous species. In nature, they feed on insects and algae, so to maintain health in the aquarium, their diet should include both animal and plant components. They readily consume high-quality dry foods in the form of flakes or granules, as well as frozen foods: bloodworms, daphnia, artemia. Feeding 1–2 times a day with portions that the fish consume within a few minutes is recommended.

Breeding and Reproduction

With a pair of adult male and female, regular offspring production is highly probable. The incubation period lasts from 26 to 30 days at a water temperature ranging from 22–26°C, allowing fry to appear almost monthly in a favorable environment. As with other livebearing fish, the young are born fully formed, bypassing the egg stage, as the eggs develop inside the female's body. It should be remembered that adult fish may eat their fry, so to prevent predation, it is recommended to move the young to a separate tank.

Diseases

When water cleanliness and proper nutrition are maintained, they possess strong immunity. The main risk factors are the accumulation of nitrogenous compounds (ammonia, nitrites, nitrates) due to insufficient filtration or overfeeding. They are sensitive to sudden changes in water parameters. Prevention includes regular water changes (up to 30% weekly) and the use of quality foods.

How to choose

When purchasing, choose active fish with clean fins and no visible damage or white spots on the body. It is important to pay attention to the condition of the scales and behavior: healthy individuals should show curiosity and swim quickly. Avoid purchasing fish from aquariums with clear signs of other inhabitants dying or a large amount of debris in the water.

Compatibility

There are no pair reviews for this species yet — check tankmates in the matcher.

All tankmates

Plants and this fish

Matching water does not mean the plant will stay intact.

Frequently asked questions

The essentials: size, tank volume, water parameters and care

How big does Flag Platy get?

An adult reaches 5–7 cm in length. Plan the tank around the maximum size: the fish quickly outgrows a cramped setup.

What size aquarium does Flag Platy need?

The recommended volume is 60 L. A smaller tank speeds up nitrate build-up and raises stress levels.

What water parameters does Flag Platy need?

Temperature 20–28 °C, pH 7–8.2, hardness 10–30 dGH. Stability matters more than exact values: sudden swings are harder on the fish than a small deviation from the ideal.

How long does Flag Platy live?

Around 4 years when kept properly. Lifespan depends directly on tank volume, water quality and a varied diet.

Is Flag Platy aggressive?

Temperament: peaceful (regular). Keep this in mind when choosing tank mates.

How many Flag Platy should be kept together?

Recommended setup: mixed (solitary / pair / group). Ignoring this is a common cause of stress and disease.

What does Flag Platy eat?

Diet type: any (universal). Feed small portions that are finished within a couple of minutes — overfeeding does more harm than underfeeding.

What is the scientific name of Flag Platy?

The scientific name of the species is Xiphophorus maculatus, family Poeciliidae. It also appears in the literature as: Platypoecilus aurata, Platypoecilus cyanellus, Platypoecilus maculatus.

Similar fishes

Matched by family, categories and overlapping keeping conditions

Balloon Platy

Balloon Platy

Xiphophorus maculatus

Poeciliidae

The Balloon Platy, also called disk platy, is known in the trade as Balloon Platy. Its distinctive feature is an unusual body shape: a strongly curved, humped back and a noticeably swollen belly, present in both males…

Black Platy

Black Platy

Xiphophorus maculatus

Poeciliidae

In the trade, this cultivar is sold as Platy Black. It does not occur in nature but is an artificially developed colour variety of the common platy (Xiphophorus maculatus). Despite its name, the black colour, though…

Blue Platy

Blue Platy

Xiphophorus maculatus

Poeciliidae

The blue platy is a selectively bred form of Xiphophorus maculatus that does not occur in nature. It is sold under trade names such as Platy Blue, Blue Moon Platy, and Platy Neon Blue. Its defining feature is the blue…

Common Platy

Common Platy

Xiphophorus maculatus

Poeciliidae

The common platy (Xiphophorus maculatus) belongs to the family Poeciliidae. Its hardiness and bright colours make it one of the most popular aquarium fish. Most platys in tanks are selectively bred varieties, some of…

Other scientific names and conservation status

Other scientific names
Platypoecilus aurata, Platypoecilus cyanellus, Platypoecilus maculatus, Platypoecilus nigra, Platypoecilus pulchra, Platypoecilus rubra
Conservation status
Data deficientDD