Sailfin Molly

The Sailfin Molly, Poecilia latipinna, is one of the two most popular Mollies kept in aquariums.

King of Livebearers

The Sailfin Molly used to be nicknamed the King of Live Bearers, both because of its magnificent appearance and because breeding it is not quite as easy as some of its relatives.The male Sailfin Molly below was apparently wild caught in or near the Gulf of Mexico.

Origin

The Sailfin Molly comes from North America from the Cape Fear drainage in North Carolina, USA to Veracruz, Mexico. It has also been caught in the open sea of the Gulf of Mexico.

Length

Fishbase gives the maximum size of this fish as 15cm, but in the Brisbane River they are reported as growing up to 18 cm. In an aquarium, sailfin Mollies are generally grow to less than 10cm (four inches).

Water Conditions

This fish needs salt; it can even live in sea water and has been captured at sea, out of sight of land, and is sometimes used in marine aquariums. In some places, the normal tap water has enough salt, but if your water is fairly pure, the addition of a bit of salt is beneficial to this fish. If you add too much, you will restrict the types of fish that can be put in as companions.

In the wild it can take pH up to at least 8.4. In an aquarium, it would normally be kept in neutral to slightly alkaline water, 7.0 to 7.8. It thrives in moderately hard water.

 

Food

The Sailfin Molly is an omnivore with a preference for vegetable matter.  They relish live food like daphnia and mosquito larvae like most fish, but also eat soft algae.  A normal fish food is suitable, and some people like to supplement this with algae wafers or spirulina flakes.

Long Digestion

Mollies eat more vegetable food than most common aquarium fish. Like many herbivores and some omnivores, this fish has a long digestive tract so the food eaten stays in the fish longer. This creates problems for transporting them long distances. Many wholesalers will starve their fish for a few hours before selling them, to reduce the amount of fish wastes that build up in the bag. This is impractical with Mollies, and sometimes a dangerous level of ammonia can build up in the bag.

For most people buying these fish from a shop, there is no problem because usually people have their fish safely in an aquarium within a couple of hours.

Colours

Sailfin Mollies are available in many colours. The picture above both the origin section and the food section are of wild type "Green" Sailfin Mollies. Also available are silver, gold, orange and black. Not all Sailfin Mollies bought in shops are pure Poecilia latipinna . 

At least some of the black ones may include a cross with  Poeilia sphenops , the so called “Black Molly”, several generations back in their ancestry.

Companions
Sailfin Mollies can be kept as a community fish as long as you choose suitable companions.  Mollies are a little bigger than many of the small fish often kept together, and care is needed to choose similar sized companions.

I have kept small Sailfin Mollies with Neon Tetras, but they are not ideal companions.   This is not just the size difference, but also the different water preferences.   Mollies are generally peaceful fish, but I avoid putting them with Siamese Fighting Fish.   I know of one case where two male Sailfin Mollies were kept with a male Siamese Fighting fish and repeatedly attempted to mate with it.  Eventually the Mollies harried the poor fighting fish to death.
Some possible companions for Mollies are Glass Bloodfin Tetras, Emperor Tetras, Black Widow Tetras, Peppered Catfish, Swordtails and Platies.  The Guppy and the Endlers Guppy are special cases as explained under Breeding.

Hybrids

Because of the ease of breeding inter-specific hybrids within the genus  Poecilia, many fish available in shops are not of pure species.

Sexing

Like their relatives, male Sailfin Mollies have an elongated anal fin while the anal fin of the females is triangular. When mature, the males also have the magnificent dorsal fin that gives them their common name in English. in the picture below, the female is above the male.

Breeding

Within the genus Poecilia , many of the species can hybridise. Unless there is a special reason, serious aquarists generally avoid producing hybrids. If Guppies are kept with Sailfin Mollies, they hybridise readily, producing a surprisingly drab looking fish. These are reported to sometimes be fertile.

As with most of the live bearers of this group, Sailfin Mollies are easy to breed, but not quite as easy as fish like the Guppy and Platy.

Mollies are sensitive to day length and often require a minimum day length of thirteen hours to breed. The light can be natural, artificial or a combination of both.

Scientific Names

The only current valid, accepted scientific name of the Sailfin Molly is Poecilia latipinna, (Lesueur, 1821). Over fifty years ago when I first started keeping this fish, it was called Mollienesia latipinna, (Lesueur, 1821).

It has also been called Poecilia multilineata ( Lesueur, 1821), Poecilia lineolata (Girard, 1858), Limia poeciloides (Girard, 18580 and Limia matamorensis, (Girard, 1859 ).

Least Concern

The IUCN has evaluated this widespread species as one of least concern.

Pest Fish
Any fish released or that gets away and gets into natural waterways is a potential hazard to the native fish of the habitat.  In some parts of Queensland Mollies are becoming a problem.  In Queensland, Mollies can legally be kept in aquariums, but not in situations where they can get into natural water ways.

Sources and Picture Credits
I gratefully acknowledge information from a Fish Note of the Queensland Government, Aquarium Life, Aquatic Community, as well as Fish Lore, FishBase and IUCN.