TankBud

Giant sailfin molly

Poecilia velifera

Also known as Yucatan molly

FreshwaterBrackishFish

Giant sailfin molly (Poecilia velifera)
Matteo Cassella · CC BY-SA 4.0

Care at a glance

Temperature
75–82°F
24–28°C
pH
7.5–8.5
Adult size
5.9 in
15 cm
Minimum tank
30 gal
113 L
Temperament
Mostly peaceful
Social behavior
Social
Swim level
Middle
Difficulty
Medium
Breeding
Livebearer · Easy
Rarity
Common
Family
Poeciliidae
Origin
Yucatan Peninsula, southeastern Mexico (Yucatan, Quintana Roo, Laguna de Terminos systems)

Overview

The giant sailfin molly is a big, mostly peaceful livebearer for a roomy tank with hard, alkaline water. It is a step up from the easiest livebearers.

Did you know

The giant sailfin molly's sail is mostly for show. Males raise and flare the big dorsal at females and rival males in a slow display. The fin only reaches full size with room to grow, and males crowded as youngsters stay stunted with a smaller fin for life.

Caring for the giant sailfin molly

Keep giant sailfin mollies in 30 gal (113 L) or more, and more if you can, with a long footprint of about 90 cm. Plant the tank well and leave open swimming room down the middle, where they spend most of their time.

Keep the water warm, hard and alkaline, at 75 to 82°F (24 to 28°C) and a pH of 7.5 to 8.5. Soft, acidic water makes them shimmy, clamp their fins and sicken, so skip the blackwater community look. Many keepers add a little marine salt, which they tolerate and often appreciate. Feed an algae-heavy diet with vegetable matter alongside regular foods.

Keep them in a group with two or three females per male, since a lone male pesters females without a break. Giant sailfin mollies are mostly peaceful. Their size and constant mating drive make them a poor match for timid nano fish.

Males grow a tall, fan-shaped sailfin dorsal. Giant sailfin mollies bear live young and breed on their own with no effort. Give the fry plants or cover, or the adults will eat them. Never release unwanted fish into local waters, and check your local rules first.

Good to know

Poecilia velifera is a livebearer in the family Poeciliidae and the largest of the common mollies. It is also called the Yucatan molly.

In the wild

Giant sailfin mollies come from the coastal lowlands of the Yucatan Peninsula in southeastern Mexico. Their range covers the Yucatan, Quintana Roo and Laguna de Terminos systems. These are hard, alkaline waters, often with some salt mixed in near the coast.

Weekly picks

Tank mates

The giant sailfin molly is a mostly peaceful, social species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a giant sailfin molly need?

A giant sailfin molly needs at least 30 gal (113 L). It spends most of its time in the middle.

What temperature and pH does a giant sailfin molly need?

A giant sailfin molly is comfortable at 75–82°F (24–28°C) with a pH of 7.5–8.5.

What does a giant sailfin molly eat?

A giant sailfin molly eats an algae-heavy diet with vegetable matter, alongside regular foods.

How big does a giant sailfin molly get?

An adult giant sailfin molly reaches about 5.9 in (15 cm).

How can you tell a male giant sailfin molly from a female?

Males grow a tall, fan-shaped sailfin dorsal.

How does a giant sailfin molly breed?

Giant sailfin mollies bear live young and breed on their own with no effort. Give the fry plants or cover, or the adults will eat them.

Related species