Product Details

Black Molly – Poecilia latipinna

Overview:

The Black Molly is a classic livebearer with a deep velvety black body, active behaviour and hardy community appeal when kept in the right water. Listed here as Poecilia latipinna, this form is best treated as a Sailfin Molly-type black strain, needing more space and harder, more alkaline water than smaller platies or guppies. Mollies are peaceful, attractive and easy to feed, but they are not ideal for soft acidic aquariums and should be kept in clean, mineral-rich conditions.

Key Identification:

Common Name: Black Molly
Other Names: Black Sailfin Molly, Sailfin Black Molly, Jet Black Molly, Molly
Scientific Name: Poecilia latipinna
Fish Type: Livebearer / Molly
Water Type: Freshwater; tolerant of slightly brackish conditions

Natural Range & Habitat:

Wild Poecilia latipinna is native to North America, from the Cape Fear drainage in North Carolina, USA, south to Veracruz, Mexico. FishBase records it from still or gently flowing warm water, including small creeks, drains, ponds, lakes, sloughs, vegetated backwaters, tidal ditches and brackish canals.

The Black Molly is a captive-bred colour form, so aquarium care should focus on the species’ preference for warm, hard, alkaline, clean water and plenty of plant or algae-based foods.

Appearance & Adult Size:

Black Mollies are known for their solid black to charcoal body colour. In Sailfin Molly-type fish, males may develop a tall, sail-like dorsal fin, which is the key feature of Poecilia latipinna. Females are usually larger and fuller-bodied, while males are slimmer and have a gonopodium.

Adults commonly reach 8–12 cm in aquariums, with large males potentially bigger. FishBase lists P. latipinna at up to 15 cm TL for males or unsexed fish and 10 cm TL for females.

Aquarium Suitability:

This is a good fish for peaceful hard-water community aquariums, livebearer tanks and planted setups with stable water chemistry. Mollies need clean water, good oxygenation, open swimming room, plant cover and a diet with plenty of vegetable matter. They are not suitable for soft acidic aquariums, small nano tanks, aggressive predator communities or neglected aquariums with poor water quality.

Recommended Aquarium Size:

A practical minimum is 120 litres for a small group, with 150 litres or more preferred for Sailfin Molly-type adults, mixed-sex groups or community aquariums. A tank length of at least 90 cm is recommended, especially for males with developed dorsal fins and active breeding behaviour.

Water Conditions:

Temperature: 24–28°C
pH: 7.2–8.5
Hardness: Hard to very hard preferred
Additional Notes: Mollies should be kept in mineral-rich, alkaline water. Seriously Fish states that P. latipinna must be maintained in moderately hard or harder water with a basic pH, as it weakens rapidly in soft or acidic conditions. Salt is not essential for healthy mollies in good hard freshwater, although this species naturally tolerates brackish habitats; TFH notes that salt can be useful in some health situations but is not required for fancy mollies and can limit plant growth.

Temperament & Tank Mates:

Aquarium Category: Community Fish

Black Mollies are peaceful but active livebearers. Suitable tank mates include platies, swordtails, other mollies, rainbowfish, peaceful barbs, larger danios, bristlenose plecs, hard-water tolerant Cory-type catfish and other calm community fish that enjoy neutral to alkaline water.

Avoid soft-water species that need acidic conditions, large predators, aggressive cichlids, persistent fin-nippers and tiny fish or shrimp that may be harassed or outcompeted. Keep in groups, ideally with one male to two or more females if mixed sexes are kept, as males can chase females. Male-only groups can work in display aquariums if there is enough space.

Feeding:

Black Mollies are omnivores with a strong need for plant and algae-based foods. Offer quality livebearer flakes, spirulina flakes, algae wafers and small granules as the staple diet. Supplement with frozen or live foods such as daphnia, brineshrimp, cyclops, mosquito larvae and occasional bloodworm. FishBase records wild P. latipinna feeding mainly on algae, with additional rotifers, small crustaceans and aquatic insects.

Behaviour in the Aquarium:

This is an active upper and midwater fish that grazes constantly over plants, décor and algae films. Males display to females and rival males, especially if they have developed sail-like dorsal fins. Females give birth to free-swimming fry rather than laying eggs, and fry may survive in planted aquariums if cover is available.

Care Notes:

Keep in stable, mature water with strong filtration, regular water changes and good mineral content. Avoid overcrowding, as mollies are sensitive to poor water quality and can develop stress-related problems in unsuitable conditions. Provide plant cover, but also leave open swimming space. A secure lid is recommended, as active livebearers can jump. If you do not want uncontrolled breeding, keep males only or have a plan for fry.

Recommended For:

Beginner to intermediate

Availability:

Common / Captive-bred colour strain

Image Disclaimer:

All images are a visual representation of the fish you will receive, made to be as accurate as possible. Natural variation in size, colour, fin shape, dorsal fin height and markings can occur between individual fish.