Marble Lyretail Molly (Poecilia sphenops)

marble lyretail molly

Marble Lyretail Molly, also known as Poecilia sphenops, common molly, Giant Lyretail Molly, Mexican Lyretail Molly, shortfin molly, or Yucatan Molly, originated in Mexico and northern South America and has since been introduced to much of Central and North America, where they can now be found throughout the U.S., Canada, and the Caribbean Islands.

These fish are popular among aquarium owners for their attractive appearance, calm demeanor, and ease of care, making them an ideal choice for first-time fish owners.
Poecilia sphenops is one of many members of the Poeciliidae family found in Mexico and Central America, where it lives in clean, shallow bodies of water with vegetation on or near the surface.

This fish’s behavior includes schooling and living in groups, with juveniles being more gregarious than adults.

Marble lyretail mollies are beautiful fish that make wonderful pets, but they aren’t for everyone. This article will explain how to care for marble lyretail mollies, and help you decide whether or not these fish will be happy and healthy in your home aquarium.

Origin and description

A few varieties of Mollies appeared in the 1920s, after Mollies were first introduced to the hobby in 1899. The male of this species of Molly will only reach 3 inches, while the female will reach 4 inches, making it the smallest of the three species.

As a result, many colors and fin varieties have been developed based on their natural form, which is blue with yellow or red fins. Marble Lyretail Mollies have large tailfins with large edges and are black and white.

The pH level of the water and the temperature should both range between 70 oF and 82 oF for these fish to be kept in captivity. Plants, gravel, and open spaces for swimming should be provided in the tank.

It is not recommended to keep different Molly species together as they are prone to hybridization. They can be kept in community aquariums with other peaceful fish, but they should not be housed simultaneously with other peaceful fish. Three females and one male should be kept together in a group.

Perlmutt Cichlid (Labidochromis perlmutt)

Species profile

marble lyretail molly

The marble lyretail molly is a live-bearing fish species that can be found in the Amazon and Orinoco River basins. It also occurs in other parts of Central America, northern South America, and southern North America.

In these areas, it can be found inhabiting creeks, pools, and slow-moving streams with sand or mud bottoms. Its habitat ranges from full sun to shade with an average temperature of 24 to 26 degrees Celsius (75 to 79 degrees Fahrenheit).

These fish feed on algae, crustaceans, insects, and small benthic animals. The marble lyretail molly reaches sexual maturity at around eight months old.

Scientific name

The scientific name of the marble lyretail molly is Poecilia sphenops.


The marble lyretail molly prefers water that is more alkaline and has a pH value of 8.0 to 8.5 with temperatures ranging from 24 to 28°C (75 to 82°F). They are found in clear, shallow, sluggish pools or ponds with a lot of vegetation and near vegetation to hide in.

Marble lyretail molly size and weight

Males grow to a maximum length of 8 cm (3.2 inches) while females grow to 12 cm (4.8 inches), and they can weigh up to 13 g (0.46 oz).

Tank size

The marble lyretail molly is a schooling fish and should be kept in a group of at least 4 individuals which comprise 3 females and 1 male. In order to keep the school size appropriate, you will need a tank that is at least 50 gallons (189 liters) in size. However, the minimum recommended tank size for a single marble lyretail molly is around 30 gallons (114 liters).

Tank mates

The marble lyretail molly is a pretty, peaceful fish that will do well in a planted tank. They like to eat algae and detritus, so they make good companions for other bottom dwellers, like other poecilia and rainbowfish.

The marble lyretail molly can also be kept with small non-aggressive and hard water-tolerant fish like guppies, barbs, and tetras.


marble lyretail molly

Mollies are known for their quick reproduction, which is among their best characteristics. It is a livebearer, meaning that females can give birth to more than 100 relatively large live young at once.

Poecilia mexicana (Shortfin Molly Fish)

Several floating plants should be present in a 50-gallon (189 liters) breeding tank, the water temperature should be about 79 degrees F and the tank should have 2 to 3 females per male. The gestation period for these livebearers is around 2 months.

Keep your fish safe and provide cover for the fry by filling the tank with fine-leafed plants like Java moss. You should always find adult female mollies pregnant, and fry will appear as soon as you get the water chemistry right.

Females bear between 10 and 100 young every 60 to 70 days, each measuring about one and a half inches in length. You can promote rearing outside of your breeding tank by placing floating plants in the corner.

Since the adult fish eat their young, it’s a good idea to separate them in a grow-out tank or breeder box unless the tank is very heavily planted. Young mollies should be fed powdered foods until they are big enough to be placed in the main tank and foraged alongside the adults.

The female should never be placed in a breeding box. Stress can easily lead to premature releasing of the young or miscarriage! Ensure there is plenty of covers and no too active tankmates in the main aquarium so that a pregnant female can live there comfortably.

Are they aggressive or peaceful?

The marble lyretail molly is on the less aggressive side, meaning that they can live peacefully in the same tank as other community fish. That being said, these mollies are still territorial and will sometimes fight with other fish of the same species. They are generally peaceful with other fish, but still require a good amount of space to avoid fighting.

Marble lyretail molly care information

marble lyretail molly

Marble lyretails are hardy fish that can do well in a variety of water conditions. They will thrive with frequent feedings, a clean tank, and plenty of plant cover. You’ll want to add a dark hiding place for the mollies to retreat to when they’re feeling stressed.

Dalmatian Lyretail Molly (Poecilia latipinna)

Provide an aquarium-safe decoration or piece of driftwood for them to hide behind. Be sure to provide some heavy plants or tall decorations like live plants because marble lyretails spend most of their time near the bottom. A filter is not necessary if you keep your tank clean on a weekly basis but is recommended if your schedule doesn’t allow you to maintain it on a regular basis.

What they eat

This type of fish is an omnivore, so make sure you’re feeding them a diet rich in both plants and meaty foods like brine shrimp, plankton, and bloodworms.

Tank requirements

Marble Lyretail Molly makes a peaceful addition to most aquariums with its handsome black and white coloring. A hard, alkaline water environment is more favorable for these types of molly fish, and they may not thrive in an aquarium with acidic or soft water.

In the aquarium, Marble Lyretail Molly can adapt to different salt levels. You can keep them in either a freshwater aquarium or a saltwater aquarium through gradual acclimation. To maintain optimum health in a freshwater aquarium, the amount of aquarium salt should not be less than a teaspoon per gallon.

It is essential that they are kept in an aquarium with algae and enough space for swimming that is at least 30 gallons. It is fine to share an aquarium with other peaceful fish that prefer hard water with high salt levels, but a male Lyretail Molly’s tall dorsal fin will not develop if there isn’t enough space.

In contrast to the female Marble Lyretail Molly, the male has a longer dorsal fin with a pointed anal fin. Marble Lyretail Molly females, on the other hand, have rounded anal fins and pregnancy spots.

A breeding tank of 50 gallons or larger is recommended for the Marble Lyretail Molly as it is a livebearer. Plants should cover as much of the aquarium as possible or there should be an algae mat covering the bottom.

15 Popular Types Of Molly Fish With Pictures


The marble lyretail molly lifespan is a long one, with them living up to three to five years.

Parasites and diseases

This species is susceptible to a wide range of diseases, and many more are waiting to be discovered. One of the most deadly diseases for this fish is ichthyophthirius, which can cause high mortality rates if left untreated.

The Marble Lyretail Molly is often infected by this parasite as they are commonly found in dirty or poorly-maintained tanks. To keep this parasite at bay, it is advised that tank water quality be maintained at 100% with regular water changes and thorough tank cleaning.

In addition to Ichtyopthirius, there are other parasites like external parasites such as flukes, ciliates, and nematodes; internal parasites such as protozoans; blood parasites such as hemoprotozoans; and ectoparasites including leeches that might affect these fish.

Predators (What animals prey on them)

The marble lyretail molly has many predators because it is so small. Some of the animals that prey on them are larger fish and birds. They use their speed to escape from these threats. Predators that feed on them include brown bullheads, bluegills, large-mouth basses, herons, cormorants, and raccoons.

Do they make good pets?

The marble lyretail molly is a popular choice for fish hobbyists because they are hardy, easy to care for and come in many different colors and patterns. They are also relatively inexpensive to purchase and maintain.

Some pet stores may tell you that these fish make great pets, while others will warn you that they’re not the best choice. This is because they are more prone to diseases than other types of fish such as goldfish or betta fish.