Assorted Molly

The Molly is one of the best freshwater fishes for beginners.  They are hardy and easy to care for and do well in peaceful community aquariums. If kept in a healthy environment, a group of mollies will thrive and can live up to 5 years.  Minimum tank size 100 litres, adult size up to 12 cm.

Mollies are live bearers that do well in freshwater — provided water quality and hardness parameters are good. It is a good idea to stock the molly aquarium with salt-tolerant plants and tank mates, in case some salt is needed for good health.

Mollies will provide an active and social group and you will see plenty of interesting behaviors and unique personalities begin to develop. They are a simple way to add some beautiful fish to your tank.

Behaviour

Male mollies often raise their dorsal fin when threatening rival males or trying to impress potential mates.

Tank Conditions

The Molly prefers a tank of at least 100 litres with lots of strong live plants such as Java fern, Sagittaria, Vallisneria and Anubias. They require a good filtration system because of their hearty appetites and more frequent water changes.  You can add 3 to 4 mollies per additional 40 litres.

Compatibility

The Molly is well suited for the community tank because of its peaceful nature, and is compatible with other peaceful, large fish that can withstand similar water conditions (salt).  Some recommendations:

• Guppies
• Platies
• Swordtails
• Other mollies
• Cherry or Rosy Barbs
• Corydoras Catfish
• Danios
• Tetras
• Loaches
• Snails and shrimps

Fish to avoid are large or aggressive as they will try to eat your mollies, aggressive ones may attack and stress them to the point of death.

Feeding

While mollies are definitely omnivores they do best on plant-based foodstuffs. Spirulina flakes and pellets are good staples, but they can be fed meaty things like bloodworms sparingly, no more than once or twice a week at most. These should only be a minor part of their diet because they are healthier and live longer on a predominantly plant-based diet.  Since their jaws can protrude forwards to make a sort of scraping tool ideal for getting algae from plants and rocks and they may get enough algae in brightly lit tanks, otherwise the Spirulina flakes and other algae-based foods can be supplemented.  Softened salads and veggies are a good addition to their diet, and usually they particularly like blanched lettuce and cooked spinach.

Care

Mollys always do better in slightly brackish water (1 tablespoon salt per 20 litres) but it’s not a requirement.

Warning: Catfish cannot tolerate the higher levels of salt typical of brackish waters. Catfish and live plants can tolerate some low levels of salt. For these, a general rule is start with one tablespoon of aquarium salt for 20 litres of water. This is a safe dosage for most all fish and plants.

Your mollies may develop a condition called “molly disease” (or “livebearer disease”, or “shimmies”). This isn’t actually a disease because it’s caused by poor water conditions.  Affected fish will swim around less, wiggling and shimmying in one spot. Check your water parameters and correct any issues, once conditions return to normal you should see improvements in the health of your mollies.

Since mollies are particularly sensitive to nitrates, aim for nitrate levels at or below 20 mg/l and do frequent water changes.  Salt reduces the toxicity of nitrate (and nitrite) and fast-growing plants can remove nitrate between water changes.

Mollies can be prone to bacterial and fungal infections and small amounts of aquarium salt helps to keep these at bay. A dosage of around one to two teaspoons per 10 litres of water is often recommended. However, a marine aquarium salt mix will help with setting up the brackish water that they thrive on. Use a dosage of about a level teaspoon per litre of water to get a specific gravity of 1.002-1.003 at 25°C.  Ensure that pH stays steady at around 7.5 to 8.5 because mollies do better in hard, alkaline water.

Click for Fish Disease Diagnosis and Treatment at Rebel Pets.