Yucatan Sailfin Molly

(Poecilia velifera)

Scientific Name: Poecilia velifera

Common Name: Yucatan Sailfin Molly

Species Group: Livebearer

Tank Type: Community

Care Level: Intermediate

Temperament: Peaceful

Diet Type: Omnivore

Role in Aquarium: Community Fish

Max Fish Length: 6 (inches)

Min Aquarium Size: 27 (gallons)

Native Range: Southeastern Mexico (Yucatán Peninsula)

Min Temperature: 72°F

Max Temperature: 82°F

Min pH: 7

Max pH: 8.5

Min GH: 15 dGH

Max GH: 35 dGH

Min Group Size:

Breeding: Moderate

Lifespan: years

The Yucatan Sailfin Molly (Poecilia velifera), also called the giant sailfin molly, is the largest of the sailfin mollies. Mature males carry a huge, sail-shaped dorsal fin.
Wild fish come only from southeastern Mexico, in the Yucatán and Quintana Roo region and the lower Usumacinta and Laguna de Términos systems. It has been introduced to a few other countries.
Grows to about 6 in (15 cm) long. Males stay slightly smaller than females.
Many color forms exist, such as gold, black and albino, and some are crossed with P. latipinna.

Dorsal fin rays are the only reliable way to tell young fish apart: P. velifera has 18–19, while P. latipinna has about 14.
P. velifera is usually the bigger fish, reaching about 6 in (15 cm). Most P. latipinna stay around 4–5 in (10–12.5 cm), although FishBase records rare males of up to 6 in (15 cm).
Their ranges don’t overlap. P. latipinna lives along the US coast from North Carolina to Veracruz, Mexico, while P. velifera is found only on the Yucatán Peninsula and nearby river systems.

An omnivore. In the wild it eats worms, small crustaceans, insects, detritus and plant matter.
Accepts live, frozen and dried foods, but include plenty of vegetable matter such as spirulina flakes, algae wafers, blanched spinach or cucumber.

A tank with a base of at least 36 × 15 in (91 × 38 cm), about 27 gallons (104 liters). Bigger is better, as cramped or crowded tanks can stunt the males’ sails.
Heavy planting with some floating cover and open swimming areas.
Hard, alkaline water: 72–82°F (22–28°C), pH 7.0–8.5, GH 15–35.

Hard, mineral-rich water is essential. In soft or acidic water it soon weakens, often showing shimmying, clamped fins or fungus.
Salt isn’t required, but it does well in brackish water and can even be adjusted to full marine conditions.
Keep water quality high so males develop their full dorsal fins.

Peaceful. Good with other hard-water fish such as platies, swordtails, hardy corydoras and plecos, and some barbs and tetras.
Avoid other mollies if you want to keep lines pure, as they crossbreed.

An active, peaceful fish that spends much of its time grazing on plants and surfaces.
Males display their sails to females and to rival males.

A livebearer, but a little harder to breed than most mollies.
Keep trios of 2 females per male, as males chase females hard.
Gestation takes about 4–8 weeks. Broods are usually 20–60 fry, though up to 200 is possible.
Fry are large and eat baby brine shrimp, microworms or powdered flakes from birth. Move pregnant females to a heavily planted tank, as adults may eat the young.