Black Molly Tropical Fish Information

Poecilia sphenops
Black Molly
Behaviour Peaceful
Typical size 6cm
Max size 8cm
Tank Area Middle, top
Min Tank Size 60cm
Temp Min: 24℃ Max: 28℃
Feeding Flake, frozen, live foods, vegetable matter
pH Range 7.5-8.5
Hardness m,h,vh
Black Molly Poecilia sphenops
  • Black Molly Poecilia sphenops - thumbnail
  • Black Molly Poecilia sphenops - thumbnail

Black Molly (Poecilia sphenops)

Black Molly Tropical Fish Learn all about the Black Molly's feeding habits and food types, its behaviour, its origins, its natural habitats, is it male or female, breeding advice and information, suitable tank mates, its sizing and growth range, minimum tank size, water PH and more. Use our fish community creator tool to plan your tank set up and ensure that the Black Molly is the right fish for your aquarium.

The Black Molly is a long-standing popular aquarium fish due to its ease of keeping, breeding and tolerance of water conditions. Like many popular aquarium fish however, the species has been over bred to the point that many specimens are weak and require specific conditions in order to remain healthy. Temperature fluctuations, especially cooler temperatures leave the Black Molly prone to disease. A symptom known as 'shimmering' where the fish swims on the spot with fins clamped in an awkward fashion is a common indicator. Skin based problems such as whitespot and velvet disease are also common. The chances of these problems occurring can be dramatically reduced by the addition of aquarium salt to the water. In hard, warm water with added salt the Black Molly is a relatively hardy fish, which is easy to care for, and well suited to a community aquarium. The wild variety is blue/green with orange spots & can tolerate cooler water. Long finned and veil tail varieties are also available, as is a 'balloon molly' variety with a heavily enlarged and rounded belly. It is the opinion of Think Fish that the balloon varieties push selective breeding too far and this variety can only be described as a disabled and deformed fish which has no place in modern, ethical fishkeeping. Males may harass females so more females should be in a group than males. Can be kept in brackish water and even acclimatized to fully saline conditions. Will eat algae.

Black Molly Facts

Family Poeciliidae (Poeciliids) | Other names Molly, Lyretail Molly, Moonfish | Origin Central and South America, Mexico | Breeding Livebearers, females are fertilized internally. Will breed readily in an aquarium | Natural Water Conditions pH 7.5-8.5, medium to very hard | Natural Habitat Freshwater and brackish | Sexing Males are more slender and have an enlarged dorsal fin and pointed anal fin

Black Molly Help and Advice

If you have a question about keeping Black Molly's then please use our Black Molly help forum. Join 100's of other fish enthusiasts with 1000's of years experience between them caring for and keeping fish like these.

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Check tank mates for the Black Molly fish species

You are in the thinkfish community creator for the Black Molly fish species, you can learn all about how the tool works in assessing fish tank mate compatibility at the link provided or use the tool tips provided to guide you. Create a test fish community that includes the Black Molly species and any other types of fish or crustacean you'd like to introduce - You can assess the best companions, tank size suitability, stocking levels based on filter type and volume and possible negative interactions and warnings as you build up your aquarium.

Please do check your water type for compatibility with your fish, which can be found on the Black Molly information box above and your local water company providers website. Don't waste your money and endanger your fish!
Tank Details
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* Recent changes to stocking & filter advice October 2018
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