Poecilia velifera (Giant Sailfin Molly)

Poecilia velifera

Last updated on September 17th, 2022 at 02:50 pm

Poecilia velifera, also known as the Giant sailfin molly or Yucatan molly, is one of the largest freshwater fish in the world, native to freshwater lakes and rivers of Mexico, Belize, Guatemala, and Honduras. The fish has become popular in the aquarium trade, where it goes by names including Giant Sailfin Molly and Yucatan Molly or simply giant molly. The popularity of this species has led to overexploitation in some regions, resulting in decreased populations in others.

Poecilia velifera, also known as the giant sailfin molly, was first discovered in Mexico’s Yucatan Peninsula by Dr. Carl H. Eigenmann in 1904 and originally classified as Poecilia velifera by Regan (1906). However, it wasn’t until 1905 that Dr. Eigenmann was able to examine its sexual organs and confirm his suspicions that it was indeed a male-female pair of poecilias that he found together in the wild.

Giant Sailfin Molly, is an omnivorous freshwater fish belonging to the Poeciliidae family of mollies native to Mexico and northern Central America, such as Guatemala and Belize. It was formerly believed to be a subspecies of the Sailfin Molly (Poecilia latipinna), but has since been classified as its own species due to genetic differences in some of its mitochondrial DNA sequences compared to Poecilia latipinna.

Origin and descriptions

Poecilia velifera are originally from Mexico, but have since spread across North America. They are also known as Mexican mollies, Yucatan mollies, and broad-striped mollies. These fish can be found in a wide range of body colors with unique patterns.

Giant sailfin molly fish are generally larger than other varieties of its species; their average adult size is about 7 inches in length and their bodies are usually colored a dark green or brown with dark stripes. The males tend to have more intense coloration than females.

The males also develop longer fins that they use to attract females during mating season. Some people believe that giant sailfin mollies are aggressive toward other fish and should only be kept with others of their own kind, while others say they’re quite social and do well in community tanks. In either case, it’s important to introduce them slowly into an established tank so they don’t get stressed out by too many changes at once.

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Species profile

Poecilia velifera

Poecilia velifera is a species of fish in the Poeciliidae family. They can be distinguished from Poecilia latipinna by their greater size and horizontal stripes along their sides.

Giant Sailfin Molly is an omnivorous freshwater fish native to Mexico and northern Central America, such as Guatemala and Belize.

It was formerly believed to be a subspecies of the Sailfin Molly (Poecilia latipinna), but has since been classified as its own species due to genetic differences in some of its mitochondrial DNA sequences compared to Poecilia latipinna velifera and has been introduced to many countries outside its native range, including Australia, Japan, Thailand and parts of Africa.

In some areas, they have become an invasive species due to their ability to breed quickly in high densities and because they compete with local species for food sources. The introduction of these poeciliids into new environments may cause damage to ecosystems through predation on native fish populations.

In 2015, it was reported that scientists had successfully bred Poecilia velifera and Poecilia latipinna together to create a hybrid, dubbed a super molly. The hybrids have been found to be fertile and grow larger than either of their parents, reaching up to 2 inches in length. These hybrids may be used as an alternative food source for humans or as baitfish due to their high survival rate when raised on farms.

Common names

Poecilia velifera are also called Yucatan molly and the giant sailfin molly amongst aquarists.


They inhabit both fresh and brackish water around river estuaries and coastal regions throughout Yucatan Peninsula, Mexico.

They also prefer an aquarium with a strong water current and plenty of hiding places like rocks and caves. The Giant Sailfin Molly must be provided with live plants, not plastic or silk.

An under-gravel filter is required for good water quality. Like most fish, Poecilia velifera are sensitive to changes in water chemistry and temperature so a heater should be used in colder climates. It’s important to test your water often because it may contain natural dissolved gasses that are harmful to fish.

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Poecilia velifera size

The Yucatan molly can grow to a maximum size of 7 inches (18 cm) in length.

Tank size

Poecilia velifera

Due to their big size, the minimum recommended tank size is 30 gallons (114 litters)

Tank requirements

The Poecilia velifera is a medium-sized fish that grows up to 7 inches and can reach weights of 1.5 pounds. They will thrive in tanks with temperatures of 70-80 degrees Fahrenheit or above, and they need pH levels between 6.5-7.5 to survive. They are saltwater fish, meaning they require a lot of salt in their water and brackish/saltwater tanks are ideal for them.

For optimal health, you should have around 30 gallons per molly in your tank. If you want to keep more than one molly together, make sure you have at least 55 gallons per pair of them. These fish are schooling fish and do best when kept with other mollies; if you only plan on keeping one giant sailfin molly, it would be best if it was kept alone in its own tank.

It’s important to remember that these fish are very active swimmers and need plenty of room in their tank. Their large fins also mean they need a lot of space so they don’t get stuck behind decorations or plants. While some people have been able to successfully keep these fish in smaller tanks, most people agree that anything less than 30 gallons is too small for them.

Poecilia velifera tank mates

The Yucatan molly is known to be a gentle fish and can be kept with other species of fish. Some common tank mates include swordtails, gouramis, Corydoras, and loricariids. That being said, it’s always important to do your research when you are introducing new fish into your aquarium.


Poecilia velifera

Compared to some livebearers, breeding Poecilia velifera can be difficult. As the males can be quite aggressive in their quest for mates, it is recommended to keep this species in trios of two females and one male. The species reproduces in a typical livebearer manner.

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The gestation period can last between 4 to 8 weeks, producing up to 200 young. In most cases, however, the number of young is 20-60. From birth, these can accept brine shrimp nauplii, microworms, or powdered flake.

For the fry to survive predation by their parents and other fish, the breeding tank should be heavily planted. Until the female gives birth, gravid females should be kept in a separate tank. It is interesting to note that wild fish rarely consume their offspring compared with domestic varieties.

Are they aggressive or peaceful?

Giant Sailfin Mollies are known for being a very peaceful community tank fish. They don’t bother other fish and will even defend their tank mates if they feel like their space is being invaded.

Poecilia velifera care

Poecilia velifera

Aquarium water should be kept clean and filtered. A temperature of 72–78°F is best for Poecilia velifera. Levels of pH between 7.0 and 8.5 are acceptable, with a specific gravity of 1.020 to 1.025 being optimal. High nitrate levels should be avoided, as well as high carbonate hardness levels, which cause excessive calcification in these fish; aquariums with large amounts of driftwood should also be avoided.

Water changes are still important to keep your aquarium healthy and clean. Use a gravel siphon in between water changes to make sure you’re not losing any vital minerals from your tank. Because of their biological makeup, Giant Sailfin Mollies are sensitive to highly acidic or alkaline waters, so it’s important that you test these levels before adding them to your aquarium.

Poecilia velifera diet

The giant sailfin molly is an omnivore that will eat most prepared foods, including frozen bloodworms, brine shrimp, tubifex worms, flake food and sinking pellets. It will also eat live foods such as blackworms or mosquito larvae.


They can live up to 5 years or more in captivity, with good water parameters and proper care.

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Parasites and diseases

Yucatan molly fishes are one of several species of fish that can get sick or die if kept in a tank with parasites. It’s important to understand which ones can affect your pet and take steps to stop them from getting into your tank. Before starting an aquarium, do research about common tank mates for your type of fish and how they’ll interact in a shared habitat.

It’s also important to use care when choosing fish—and keep an eye on any new additions! You may not know right away whether something is wrong with your fish, but you should be able to tell when something is off. If you notice changes in behavior or appearance, seek out help as soon as possible. Your veterinarian will be able to perform tests and recommend treatments based on what he finds.


Some common predators of the giant sailfin molly in their natural habitats are birds, such as herons and egrets. Other potential predators include larger fish, such as largemouth bass and bluegill. These fish can be prevented from eating your poecilia velifera by hiding them in a tank with a lid or covering it with plants.

Do they make good pets?

Yes, Poecilia velifera make good pets. These peaceful fish come in a wide variety of colors and are easy to take care of. They can grow to be 7 inches long, but will rarely reach that size unless they live in an aquarium with other poecilia velifera fish. These fish are omnivores and will eat just about anything you give them—shrimp pellets, bloodworms, freeze-dried tubifex worms, and even flake food.