Short-finned Molly, Sailfin Molly, Mexican Sailfin Molly

Family: Poeciliidae Picture of a Silver Lyretail MollySilver Lyretail MollyPoecilia sphenops
Latest Reader Comment - See More
Mollys are very cool fish. You can make your own combinations by breeding them. For example get a marbled molly and breed it with a Orange Balloon Molly and the... (more)  Iv

   The colorful active Molly, Short-finned Molly, Sailfin Molly, or Mexican Sailfin Molly has long held the position of being a most popular fish because it is peaceful, relatively hardy, inexpensive, and readily bred!

Whether you have a Short-finned Molly Poecilia sphenops, a Sailfin Molly Poecilia latipinna, or Mexican Sailfin Molly Poecilia velifera these are truly staples for the beginning aquarists aquarium. This is because the Molly has so many good qualitites. It is peaceful, relatively hardy, inexpensive, and will readily bred.

Mollies are strictly American fish, found only on the continents of North and South America. The first Molly was introduced to the hobby 1899 and hybrids began being produced in the 1920's. The pictures here show the Short-finned Molly with a gold and silver color and the lyretail and balloon varieties. Mollies come in four main colors; green, black, silver, and gold. There is also commonly available a silver molly with black spots that is call the Dalmation Molly and a Marbled Molly with the same (white and black) colors.

Wild caught mollies fall into two groups. The first group is the Common Molly with small fins, which is also called the Short-finned Molly. The second group is comprised of the sailfin type mollies with large fins. This group includes two species, the Sailfin Molly Poecilia latipinna and the Mexican Sailfin Molly Poecilia velifera. The fin size is one way to distinguish these two groups. Another easy way to distinguish between the short fin and sailfin groups is by the location of their dorsal fins. On the Sailfin Mollies the dorsal fin is situated in front of the anal fin, while on the Common Mollies this fin starts behind the anal fin.

Distinguishing between the two types of Sailfin Mollies is more difficult because their coloring is very similar. Often they can only be distinguished by the number of rays on the dorsal fin. The Sailfin Molly, P. latipinna has about 14 rays and the Mexican Sailfin Molly, P. velifera will have closer to 18 rays.

For beginners the Short-finned Molly is the best choice as it is the most durable, least demanding, and needs the least space. The next best choice is a cross breed of Short-finned and Sailfin. The Sailfin Mollies, though often more peaceful, are a bit more challenging to keep. In general all mollies are peaceful, though it has been noted that behavior is very individual, and occasionally you will get a fish that can be quite ornery.

All Mollies need an aquarium that is well planted and not overcrowded. It is suggested that you add a little salt and that you provide lots of algae and other vegetable foods. The use of breeder traps is hazardous to these fish, and it is recommended that you provide floating plant cover for the fry instead.

Mollies got their common name from the fact that they used to be in the genus Mollienesia.

What's in the name?
Poecilia means "many-colored"
sphenops means "wedge appearance"
latipinna means "broad fin"
velifera means "sail-bearing"


For more Information on keeping this fish see:
Guide to a Happy, Healthy Freshwater Aquarium

Geographic Distribution
Poecilia sphenops
Data provided by
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Cyprinodontiformes
  • Family: Poeciliidae
  • Genus: Poecilia
  • Species: sphenops
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Mollies - Quick Aquarium Care
  • Size of fish - inches: 8.0 inches (20.32 cm)
  • Minimum Tank Size: 15 gal (57 L)
  • Temperament: Peaceful
  • Aquarium Hardiness: Moderately hardy
  • Temperature: 72.0 to 82.0° F (22.2 to 27.8° C)
  • Aquarist Experience Level: Beginner
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Habitat: Distribution / Background

   Mollies mostly inhabit coastal waters from southeastern North America south to Venezuala, but they have been found in the ocean as well as in brackish and fresh water.
   The Short-finned Mollies, P. sphenops are found from Mexico to the northern part of South America.
   The Sailfin Mollies, P. latipinna, are found along the southeast coast of the United States and the Gulf of Mexico. These are the most common large fin molly as they are easily obtained, inexpensive, and prolific breeders.
   The Mexican Sailfin Mollies, P. velifera come the coastal area of Yucatan, Mexico. This Sailfin is more rare in the hobby because it is not as easily obtained as the P. Latipinna. It is also more difficult to breed and the tank bred often do not have the impressive dorsal and tail finnage. Better success is obtained in ponds.

Most mollies available today are selectively bred or are hybrids:
   Most often the large-fin types are cross breeds of the Short-finned Molly, P. sphenops and the Sailfin Molly, P. latipinna. These cross breeds include the lyretail, moonfish, and flag. It is from the "sailfin" species that albino coloring is obtained.
   The popular "Black Molly", a selectively bred Short-finned Molly, P. sphenops, appeared in 1909 in Europe but was first developed in the United States in the 1930's. These selectively bred fish are not as hardy as original fish, being more susceptible to disease and needing warmer water. Though it was first a small finned molly, it was later crossbred to produce a large finned molly in about 1976.
   The "Midnight Molly" is a selectively bred all black variety of the Sailfin Molly, P. latipinna.
   The Lyretail Molly has all normal fins except for the tail, which is long with the outside edges being longer still. The tail tends to loose its lyre shape as the fish get older. There is also a Veiltail Molly which has a long tail and dorsal fin. Sometimes the fins on this fish are so long that they have trouble swimming. Both the Lyretail Molly and the Veiltail Molly are more difficult to breed due to a very long gonopodium.

  • Scientific Name: Poecilia sphenops
  • Social Grouping: Groups - Although they will not school, Mollies enjoy lots of company!
  • IUCN Red List: NE - Not Evaluated or not listed


   Short-finned Molly, P. sphenops grows between 2.38 - 4 inches (6 - 10 cm) in the aquarium, and up to 8 inches (20 cm) in nature. Their prominent natural color being a blue body often with yellow or red fins.
   Sailfin Molly, P. latipinna grows between 4 - 6 inches (6 - 10 cm) in the aquarium, and up to 8 inches (20 cm) in nature. Their prominent natural color is a green body often with black dots and a large dorsal fin on the male.
   Mexican Sailfin Molly, P. velifera grows between 4 - 6 inches (6 - 10 cm) in the aquarium, and up to 8 inches (20 cm) in nature. Their prominent natural color is usually a green body often with dark dots and a large sail-like dorsal fin on the male, there is also often an albino strain.

  • Size of fish - inches: 8.0 inches (20.32 cm) - Few mollies will grow over 6 inches in the home aquarium, however certain species may reach up to 8 inches in the wild.

Fish Keeping Difficulty

  • Aquarium Hardiness: Moderately hardy - It should be noted that Ballon Mollies will tend to have a shorter lifespan due to their suboptimal body shape and the high degree of inbreeding. This fish is also not particularly disease resistant and as such should be spared the fluctuations of a newly set up aquarium.
  • Aquarist Experience Level: Beginner

Foods and Feeding

   These fish are considered omnivores as the Molly, Short-finned Molly, Sailfin Molly, or Mexican Sailfin Molly will generally eat all kinds of live, fresh, and flake foods. But they have a very high herbivorous requirement, in that the majority of their diet needs to include lots of algae and other vegetation. Feed brine shrimp (either live or frozen), tubifex, or blood worms as a treat. They will enjoy the proteins but they can not subsist on them, they must have a vegetation diet.

   Mollies are often found in saline waters and it is recommended that 1 to 1.25 teaspoons of non-iodized salt be added to the aquarium water. The common molly is a bit hardier and can be kept in a smaller aquarium, whereas the sailfin mollies are more delicate and need a larger aquarium with plenty of room. The sailfin mollies also do better when kept with other livebearers that can handle a saline environment. Mollies are prone to ich, fungus and other diseases if their environment is not comfortable for them.

   Provide plenty of plants and floating plant cover for munching on, and for hiding places for the fry.

  • Diet Type: Omnivore - Although this fish is an omnivore, it requires a much greater vegetable component to its diet. It is a good idea to supplement with blanched lettuce.
  • Flake Food: Yes
  • Tablet Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Most of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day

Aquarium Care

  • Water Changes: Monthly

Aquarium Setup

   Short-finned Molly, P. sphenops and Sailfin Molly, P. latipinna:
     Hardness: 20-30° dGH (absolute lowest is 11°)
     Ph: 6.5 to 8
     Temp: 75-82° F (24-28° C)
   Mexican Sailfin Molly, P. velifera:
     Hardness: 25-35° dGH (absolute lowest is 11°)
     Ph: 7.5 to 8.2
     Temp: 72-82° F (25-28° C)

  • Minimum Tank Size: 15 gal (57 L) - A single individual could be kept in a fifteen gallon tank with some company, although a better setup would be a group of 4 or more in a 25 gallon tank. Keeping several males in a smaller tank will lead to constant aggression, so it is best to keep one male with a small harem of females unless the tank is very large. The aquarium should be well planted with plenty of swimming space.
  • Substrate Type: Any
  • Lighting Needs: Moderate - normal lighting
  • Temperature: 72.0 to 82.0° F (22.2 to 27.8° C)
  • Range ph: 7.0-8.0 - These values are acceptable for the Short finned (P. Sphenops) and Sailfin Molly (P. Latipinna). The Mexican Sailfin (P. Velifera) should be kept within the range of 7.5-8.2.
  • Hardness Range: 20 - 30 dGH - The Mexican Sailfin Molly (P. Velifera) should be kept in water with a hardness of at least 25.
  • Brackish: Yes - These fish have a very high salt tolerance and it is considered beneficial to add 1-1.25 teaspoons of aquarium salt per gallon. Removed water should be replaced with salted water, however if the aquarist is topping off due to evaporation freshwater should be used.
  • Water Movement: Moderate
  • Water Region: All

Social Behaviors

   They are a good community fish.

  • Venomous: No
  • Temperament: Peaceful - This fish is generally a good community fish although males will establish a clear hierarchy and more dominant individuals might extend the hierarchy over other tankmates. This fish can have quite extensive fins which are often too tempting for fin nippers like Tiger Barbs to resist so avoid combining these fish with them in the same aquarium.
  • Compatible with:
    • Same species - conspecifics: Yes
    • Peaceful fish (): Safe
    • Semi-Aggressive (): Monitor
    • Shrimps, Crabs, Snails: Safe - not aggressive

Sex: Sexual differences

   The male is slender and has a gonopodium, the female is larger with a fuller body.

Breeding / Reproduction

   These fish will readily breed. See the description of how to breed these fish in Breeding Freshwater Fish, Livebearers.

  • Ease of Breeding: Easy


   The selectively bred varieties and cross breeds of the Short-finned Molly, P. sphenops and the Sailfin Molly, P. latipinna are readily available.


Animal-World References

Author: David Brough CFS, Clarice Brough CFS
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Lastest Animal Stories on Mollies

Iv - 2003-08-27
Mollys are very cool fish. You can make your own combinations by breeding them. For example get a marbled molly and breed it with a Orange Balloon Molly and the outcome will be cool. Buy a couple and keep the male ratio to one male for two females because the male will chase females and somewhat exuast them.

  • R.Balaji - 2013-08-25
    It's wrong. I have two males but their behavior is not like that. I am R.balaji. We can be freiends, please reply.
  • Ruben Mendez - 2014-08-04
    They are honestly very cool have a 85 gal with ballon mollys and lyretail and many more mollys and have very exotic colors...
Sarah - 2004-03-13
I love mollies! If a fish can be lively and friendly... they are lively and friendly! They follow your finger on the glass and they are always doing something silly. We have 3 females and one male. The male is a dalmation sailfin molly, and 2 of the females are silver lyretails, and the last female is also silver, but shes a sailfin too. I havent seen any fry yet...maybe because I have danios and tetras, but Im going to look next time so I can net them! I recommend them to anyone!

Henry Chua - 2003-09-24
Black Mollies were my very first pets. I adored them so much then. They are still in my top favorite list. Black Mollies look very cool, with their jet black colors. Their fries are even cuter! Basically i fed them with tubifex worms & bloodworms daily. Their parents are really protective over their offsprings and I have never seen any of their parents eaten any yet, but do provide driftwoods or hiding places for the fries.

Samuel Brown - 2004-05-14
The Sailfin Mollie is best if not bred for colors other than their natural colors. When in tanks with other fish and are also very peaceable fishes. Like most mollies the Sailfin Mollie reproduces fast in larger habitats most commonly. I know this from observation of this animal in both wild and domesticated states. For more suitable habitats the Sailfin Mollies (and mosquito fish)are best kept in water with a low saline or brackish water level and a ph of 6.8-8.6 with vegitation that trives in an abundant supply.

Irene - 2009-07-02
To whom it may concern,

Thank you for sharing your knowledge and expertise on mollies. I have learned much valuable information from your website. I have some mollies coexisting happily with other community fish including guppies, dwarf and Mickey Mouse platys, female bettas, one dwarf frog, and one double tail male betta. They all seem to be doing fine together. I have dalmation, orange and black regular tailed mollies. Recently I purchased some lyre tail mollies. They sure are an active fish. They constantly are speedy swimmers and aggressive breeders. I now have some babies from these fish and they are so cute! I have a silver male lyre tail molly that is often chasing the female fish. He is the stud of my tank so I call him Fabio. He is sometimes chasing the other males and I assume this is his way to get them away from his girl mollies. Luckily I have more females then males so no single female molly is singled out as that would lead to unnecessary stress. For later reference, I have organized your website and other related websites that I may need later.


Irene Steffen


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