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.

question mark     

Check Tankmates for the Black Molly fish species

Create a test community that includes the Black Molly fish species and other types you'd like to introduce - Assess tank size suitability based on filter type and volume, possible negative interactions and warnings.

Please check your water type for compatibility with your fish, which can be found on the Black Molly information box.
Tank Details
question mark  Rename your tank:
question mark  Length: (cm)
question mark  Volume: (Litres)
question mark  Filter type:

* Recent changes to stocking & filter advice October 2018
* This fishtank will only last for this session - to save your tank please Join/Log in

question mark  Max Stocking level: 0cm
0-1 months 20%: 0cm
1-3 months 40%: 0cm
3-6 months 60%: 0cm
question mark  Current stock level: 0cm
Stock percentage: 0%
question mark  Suggested maximum
fish size for your tank:
My Fishtank Quantity Stock cm
There are no fish in your fishtank. To add fish, view a fish profile and click the 'Add to My Fishtank' button

If you'd like to talk about the "Black Molly" with our users, then we have a buzzing community of fish enthusiasts where you can talk about tank issues, Black Molly fish behaviour, Black Molly tank stocking and any other issues related to the Black Molly fish or other types you may have.

To save your details in the Fish Community Creator you must be logged in CLICK HERE to log-in or join

Help us keep great tools like this online by becoming a think fish supporter . You will help with our hosting and development costs. From as little as £1.16 per month - Become a Supporter today

Click to read the Latest Tropical Fish discussions from Thinkfish users.

Think Fish Tropical Fish Forum
Tropical Fish Market Place
Fish of the month

Helping Fishkeepers With Their Fishkeeping Needs Since 2006