Black Sailfin Molly – All You Ever Need to Know

A black sailfin molly is a blackened breed of the sailfin molly that is black all over. It is one of the most well-known aquarium fish, nearly prolific and also as easy to keep.

If you have doubts about keeping a black sailfin molly fish due to lack of information to maintain this beautiful and intelligent species. I tell you, many people have successfully cared for a black sailfin molly.

This article contains adequate information you require in keeping a black sailfin molly in an aquarium. Also, most questions related to a black sailfin molly are answered in this article as you read further.

Some names of black sailfin molly in other languages include;

Zeilvinkarper (Dutch), subunits (Tagalog), breitflossenkärpfling (German), molinezja szerokopłetwa (Polish), seilfinnemolly (Norwegian), leveäevämolli (Finnish), and molliénésie á failure or simply “molly voile” (French). However, their scientific name is Poecilia latipinna

Black Sailfin Color

The black sailfin molly is an entirely melanistic form of a sailfin molly. You can also call them the common molly. However, they originally referred to the melanistic breeds of Poecilia sphenops.

This molly belong to the short-finned hybrid variation of Poecilia latipinna. That is, the sailfin molly. Also, they are all black in coloration with short fins. Typically, the juveniles may have patches of a slight gold or silver coloration. Whereby, they outgrow with age. Sometimes, you can find a trace of yellow line along their dorsal fins.

Geographical Location

The black sailfin molly (Poecilia latipinna) is a species of fish of the genus Poecilia. Also, they inhabit brackish, fresh, and salt water. And coastal waters from North Carolina to the Yucatán Peninsula of Mexico and Texas.

Although, they prefer lowland streams, swamps, estuaries, and, marshes, the black sailfin molly is very common in peninsular Florida. Nonindigenous populations are present in the western U.S, New Zealand, and Hawaii.


In most cases, you can observe sailfin mollies at the plane surface waters along the edges of marshes, ponds, swamps, lowland streams, and estuaries. However, before choosing a black sailfin molly for grooming, you should bear in mind that their males are more aggressive compared to their females. This is typical when they are feeding or mating. Also, note that these fishes are used to their natural environment. Therefore, there is a need to have proper and adequate knowledge as regards keeping them in an aquarium.

You will mostly find the species aggregating in both small and large. Therefore, you may find them under floating vegetation or near the water surface. However, this minimizes the chances of potential predators observing them.

The black sailfin molly is a species that can adapt to a wide range of environmental condition. Also, with its upturned mouth it can exploit the thin film of oxygenated water surface. Also, it can survive oxygen-deficient habitats. Although, an euryhaline species, the black sailfin molly can tolerate a wide range of salinity. Therefore, it can be found in a variety of saline environments. Typically, it can tolerate salinities as high as 87 ppt and breeding in brackish waters.

Distinctive Features of a Black Sailfin Molly

The black sailfin molly gets the majority of its traits as a result of captive breeding. Therefore, it is a struggle to find one in the wild. Typically, they have a small head, which is dorsally flattened, and a small, upturned mouth. Also, their body is essentially oblong.

Their caudal peduncle is broad and the caudal fin is round, big, and sometimes tipped with black.  Also, black sailfin mollies pelvic fins originate at a point anterior to the dorsal fin. In mature males, the caudal fin is colorful and the dorsal fin is greatly enlarged.

Although, these characteristics play a major role in female mate choices. Also, black sailfin molly forms a trapezoid when it spreads his dorsal fins in a display. Typically, the posterior edge is the shortest. This is because, the posterior edge, is a bit less than the height of the tail when you measure the height of the dorsal fin. Usually, the female is more plainly colored and it tends to be larger

Black Sailfin Molly Versus Yucatan Molly

The black sailfin molly is a smaller fish than the Yucatan molly (P. velifera). Although, that species often do not grow to full length if bred in an aquarium. Also, the most distinctive character are the dorsal fins: Those of the black sailfin molly have less than 15 fin rays, counting where the fin meets the back. Whereas, the Yucatan molly has 18-19 fin rays.

Age, Growth, And Size of a Black Sailfin Molly

Black sailfin mollies’ natural lifespan is short, predominantly in the case of the males. Which may live less than a year after achieving sexual maturity. Depending upon environmental conditions, they may become reproductive in less than a year.

Characteristically, sailfin mollies are small. Therefore, a black sailfin molly is also small. At one year of age, males typically range in size from 0.5 to 3 in (13 to 76 mm) inch. While mature females are likely to be 0.5 to 2.5 inch (13 to 64 mm). Naturally, the size of adult males directly correlates with population density.

However, black sailfin mollies rank as one of the most popular feeder fish because of reproduction, brood number, high growth rate, and birth size.

Black Sailfin Molly Diet

Unlike the other types of mollies in the fish keeping hub feeding black sailfin mollies is an easy task. However, this is because they are not picky. As their diet include a wide range of foods that you can get from most stores. Primarily, they feed upon algae, other plant materials, and some detritus. Therefore, your black sailfin mollies will prevent parasites from invading your tank, if it is prone to green algae breakouts.

Although mollies omnivorous species, it is important to include natural source of foods as much as possible. However, we recommend that they consume several aquatic invertebrates. This also includes the larvae and pupae of mosquitoes.

Feeding A Black Sailfin Molly

Mollies require a little quantity of vegetables in their foods. So as to survive. Therefore, they will eat almost every available green vegetable. But, it is better to serve them with cucumbers, shelled peas and zucchini. Also, endeavor to feed them vegetables once per week. Whereas, you can do twice per week, if possible.

Moreover, you should serve a high-quality flake food as the major food source in a black sailfin mollies diet. Also, you can include a supplement with the flake foods. Supplements can be frozen, or live foods such as black worms, bloodworms, brine shrimp, and daphnia. Normally, black mollies prefer live foods. Although, this can be difficult to find sometimes. However, in this case, you can go with frozen foods.

How Do I Feed an Aquarium Fish?

Naturally, fish eat whenever they are hungry and food is available. Therefore, if food sources are usually plentiful, they will eat several times a day. But, if food sources are infrequent, they can survive days between meals. For this reason, fishes are very opportunistic and will eat whenever they have a chance. Regardless of one or two feedings, the important thing is to keep each feeding very small. Do not overfeed your fish. Whenever you are unsure, the best thing is to underfeed your fish. This is because, a lot of health problems are related to overfeeding your fish.

Sex Differentiation in Black Sailfin Mollies

Just like many other livebearers, identifying a black sailfin molly fish is not any easier. Typically, their females are larger than males. However, you can distinguish the males base on their gonopodium. Also, they have an anal fin with a shape similar to a hook. Usually, this serves the purpose of hooking onto the female molly fish, when they are ready to deposit sperm.

Breeding Method

By following the general advice of a three female to one male ratio, breeding will be easy. Male sailfin mollies are extremely aggressive in their breeding habits. Though, you can expect some molly fry within a couple of months, as long as the tank is set up in a way that the mollies feel comfortable.

However, most people keep males and females together after impregnation. While some will move the females to a completely different tank. Although, if you are considering separating them, it is best to separate them after one week. As this will help reduce the chance of miscarriage. Moreover, mollies lack good parental care in an aquarium. This is because they will eat any fry their eyes feast on.


A black sailfin molly fertilization is internal. Therefore, this means that they hold their eggs inside their body. They do this until they can give birth to live young straight into the water. Also, their fertilization involves using highly modified fin elements. However, this is within the anal fin of males that form a structure known as the gonopodium.

Typically, they produce broods of 10 to 140 live young. This depends on their maturity and size. Also, their females may store sperm long after the demise of their relatively short-lived mates. Moreover, the gestation period of this species is about 3 to 4 weeks. Usually, this is dependent on their temperature. Also, a single female may give birth on multiple occasions throughout the year.

Although sex ratios of the broods are balanced, their adult populations tend to be more of female than male. This is because, their males seem to suffer high rates of death. And this is due to their greater susceptibility to disease and predators. Which is as a result of their wild breeding and brighter colors.

Aquarium Black Sailfin Molly Fish and Tank Set Up Guide

The most important thing to consider when setting up a tank to house a black sailfin molly is the proportion of the two sexes. Generally, black mollies are a peaceful community fish, but multiple males kept together in the same tank can be problematic. This is because, the males are aggressive. Also, when females are outnumbered by males, they tend to be harassed.

However, the optimal ratio recommended is 3 females to one male. The male mollies are aggressive breeders. Hence, providing more females will help divide the attention between them. Also, this prevents anyone female from receiving constant attention. Failure to stick to this optimal ratio, or one in that area, you may find that the females will be too stressed to eat. Potentially, this could lead to the death of the female molly.

Recommended Tank Plants for A Black Sailfin Molly Aquarium

Black sailfin mollies love planted aquariums, so the more plants you have, the better. This is because the plants will increase the survival rate of the fry. Also, it allows their adult fish to feel very relaxed. However, they are known to be notorious when it comes to feeding their fry. Therefore, it is important to give them a place to hide. Also, this will aid your breeding enormously. Generally, any plant will do the trick, but here are a few of the ones usually recommended:

Amazon sword

Java moss

Java ferns


General Tank Requirements of a Black Sailfin Molly

It is often thought can survive best in saline waters, but that is not the case at all. Although, it is true they can survive in almost any water condition, they should be kept in freshwater tanks. Naturally, black sailfin mollies love having enough space to move. Also, you will need a tank that is big enough to accommodate them in as much as you will be keeping them in larger groups. Usually, this is to prevent any unnecessary harassment or aggression. At least 20 gallons should be minimum, but if possible, a 45-gallon tank will be a lot better.

For the pH and temperature, we recommend that you keep your black sailfin mollies in water that is between 70 and 80 degrees Fahrenheit. Also, in a pH that is closer to the harder, more alkaline side of the spectrum (7.5 – 8.2). However, you must keep the tank environment as steady as possible. This is because, they are sensitive to changes in water parameters.

Tank Mates of A Black Sailfin Molly

The black sailfin molly is known to be peaceful. Also, they are also a community fish and can live well with other peaceful, community fish. Some of the fish that can be kept with a black sailfin molly include:




other Mollies




Female Betta Fish.

Generally, they will lie harmoniously with other livebearers. Although, livebearers have a status for eating their offspring. So, if you are interested in breeding livebearers in a community tank, make sure there are plenty of plants as recommended above, for the fry to hide.

Filtration for Black Sailfin Molly Tanks

Any type of filter will work well when keeping black sailfin mollies. However, it is completely dependent on what you have access to, or what you can afford. Majorly, other fish keepers will recommend a canister filter, which is good too. We believe they are a little too expensive when it comes to keeping black sailfin mollies.

However, a simple hang on the back filter is cheaper, and will not disturb the water apparent as much as most other filter types. Also, we recommend choosing a filter that leaves the surface as plane as possible. This is because mollies naturally love to swim on the surface, looking for floating food.

How to Care for A Black Sailfin Molly

Black sailfin mollies are some of the toughest and more adjustable fish out there. Also, just like any other fish, the big thing is a clean tank. You need to know how to clean effectively. This includes checking that ammonia and nitrites are at 0ppm and also monitoring the water conditions.

Your black sailfin mollies may develop an ailment called “molly disease” (or “livebearer disease”, or “shimmies”). This isn’t a disease. This is because, it is caused by poor water conditions.

Moreover, the affected black sailfin molly fish will swim around less, squirming and shimmying at one spot. Therefore, you should check your water condition and correct any issues. Although, as soon as the conditions return to normal you should see improvements in the health status of your mollies.

However, one of the important easy ways to reduce the intensity of disease is cleaning the tank and interchanging their diet. Furthermore, there are treatments that you can purchase from stores, if the problems persist.

Some Fish That You Should Avoid Keeping with A Black Sailfin Molly Include;

Delicate species – This is because male black mollies are usually aggressive, with large body size. So, they tend to bully tank mates. Some of these fishes include Discus, which needs to thrive in a peaceful environment, and not with a molly.

Smaller species that can be easily consumed: Try to avoid anything small including catfish. Because, it can enter a sailfin mollies mouth within a short period. Also, there are spines on the fins of a catfish that can cause death to a molly if swallowed. Generally, small species pose a threat to mollies. Especially, the sluggish ones.

Species that are sensitive to water conditions: Some species can only thrive in a pristine water condition. Black sailfin mollies are usually messy eaters, so they tend to have high nitrate levels in their tanks. Also, some species are very sensitive to water condition. And they could die when placed in an environment that doesn’t befit them.

Importance of A Black Sailfin Molly to Human

The most considerable interest and value to aquarists is the many color varieties of a molly. However, many artificially selected varieties are produced and sold in pet shops. Also, wild black sailfin mollies are bred as feeder fish for superior flesh-eating fish. Although, guppies are naturally used for that. Furthermore, the black sailfin naturally occurring populations control mosquito population by feeding on the larvae and pupae of these pests.

Interesting Facts About a Black Sailfin Molly

The black sailfin mollies are nice and peaceful fishes. They sometimes will attempt to chase others around a bit. Although, in most instances, they tend to not harm them. Mollies do best in a group of more females than males.

They are usually good tank mates for the following type of fish: Angel Fish, Catfish, Corydoras Pleccostomus, Platies, swordtails, and Bigger Tetras such as Red Series, Black Skirts, and Silver Tips.

Also, they will live on an average of 3 to 5 years and can grow to 5 inches.

There is an important allegory in Lore indicating that females may reverse their sex and become large males. This is probably because late-maturing males are physically similar to females and grow to a large size before they start to mature.

Are Black Sailfin Molly Fish Suitable for Your Aquarium?

There are not many reasons not to get black sailfin mollies. This is because, they are a great choice for community aquariums. However, bigger fishes can feed on a black sailfin molly fish.

Also, the condition of the tank is important to their health status. Therefore, the tank needs to be within their preferred range. However, they can tolerate a wide range, so they can go in lots of different tanks. Also, you won’t have a problem with their diet either, they can eat a wide variety of food types. Generally, if you have the right tank they can be easily cared for.

Therefore, you get a school of fishes that; are easy to breed, display lots of activity, and introduce lots of bright colors.


Black sailfin mollies are members of the lower end of the food chain. Fundamentally, they are prey for different animals. This includes aquatic insects, amphibians, birds, other fishes, reptiles, and mammals. Some of their predators include:

American alligator (Alligator mississippiensis),

Bullfrog (Rana catesbeiana)

Giant water bugs (Belostomatidae)

Largemouth bass (Micropterus salmoides)

Raccoon (Procyon lotor)

Snowy egret (Egretta thula).


Saccocoelioides sogandaresi is a trematode and it is a known parasite of the sailfin molly. Also, it is the ciliated protozoan Ichthyophthirius multifiliis. This causes the disease commonly known as freshwater ich, freshwater ick or freshwater white spot.


What do I feed my black sailfin molly?

Black sailfin mollies feed primarily upon algae and other plant materials. Although they will consume many aquatic invertebrates. This also includes the larvae and pupae of mosquitoes. This is a feature that makes them important to man.

Where does black sailfin molly live in the wild?

They inhabit fresh, brackish, salt, and shore waters from North Carolina to Texas and the Yucatán Peninsula of Mexico.

Are black sailfin mollies aggressive?

Yes, sailfins tend to be more aggressive than other mollies, especially the males. Also, as recommended you will always have to keep at least 3 females per male. Otherwise, they get territorial and aggressive.

Can I keep different types of mollies together?

Yes, different types of mollies can be kept together. Although, hybridization can occur between these mollies. Therefore, it is advised that you keep them in groups of at least four or more.

How many black sailfin mollies should be kept together?

Naturally they stick together, therefore, ensure you keep them in groups of at least four or more. Also, the group should consist mostly females since males are known to harass them. However, the males tend to fight for territory against each other. Therefore, do not keep only males in the same tank.

What does a pregnant sailfin molly look like?

A pregnant female molly belly will appear to be much larger and swollen than usual. Generally, this is easy to spot, especially by comparing them to other mollies in the tank. Also, you can tell by looking at their anal fin. This is because, the anal fin would show a dark gravid spot. Furthermore, an obvious increase in chubbiness should be a solid indicator that she is carrying some fry inside her.

How long do sailfin mollies live?

Typically, a black sailfin molly is often used by marine aquarists to Cycle a new tank. This is due to their salt tolerance and hardiness. Mollies will live for between 3 to 5 years, if given proper and adequate care.

What do black sailfin molly Fish babies look like and how do you care for them?

The fry of a black sailfin molly has black eyes and would usually look like small forms of the adults. Usually, you should separate the fry from other fishes (including their parents) until they have a similar size. However, a black sailfin molly baby is often half an inch in size.

How do I keep baby black sailfin mollies alive?

You should separate the pregnant black sailfin female molly from the main display aquarium, till she has released all her fry. Also, you can place the pregnant molly in a breeding box. This is done, so that the mother is trapped and the fry escape at birth. However, remove the female and return her to the main display aquarium after she has released all her fry.

How do I keep my black sailfin molly fish happy?

We recommend you keep the water temperature as steady as possible to avoid unnecessary stress for your fish. Usually, this fish prefers hard water, and thrive at a higher water pH, preferably 8.0.

Also, you should try to create a sense of connection with your molly fish. You can achieve this by playing with them. One of the popular method is tracing your fingers on the aquarium tank. The fish tends to jump towards it, which makes them active.


Remember, black sailfin mollies are beautiful living creatures. Also, they have special importance to man. So, it is the responsibility of the black sailfin owner to care for their fish, provide a healthy environment and meet all their basic tank requirements.

Therefore, give your black sailfin molly enough space, clean water, and plenty of hiding places. Also, highly varied foods should be a good companion for a long time. However, ensure to put your mollies fry in the same ideal condition, until they are too big to fit into the adult mollys mouth.