How to Keep Mollies

A tank populated with mollies can be an impressive sight. The deep black coloration of the black molly and the tall dorsal fin of the sailfin molly make them unique additions to any aquarium. Mollies (Poeciliidae) are often recommended as a beginner fish for a community tank but this is misleading. Mollies do best when kept alone or with other mollies. They require the addition of sea salt to their water in order to thrive and can even live comfortably in a marine tank if slowly acclimated to the increased salinity. They are active swimmers that can sometimes nip the fins of slower moving fish. Common colors for mollies are velvety black, silver, greenish blue, spotted black and white and gold. Mollies are available in a number of body shapes from the deep-bodied balloon molly to the more narrow and delicate lyretail variety.

Things You'll Need

Heated aquarium (10 gallon minimum)
Floating plants
Sea salt

Instructions

- 1
  Prepare a molly tank by setting the water temperature between 77 degrees F and 83 degrees F. Add a teaspoon of sea salt for every 2 1/2 gallons of water. Mollies prefer medium-hard alkaline water. They can grow to 4 inches, so avoid tanks smaller than 10 gallons.
- 2
  Add floating plants to the water, and cultivate algae by making sure the tank receives some bright indirect light each day.
- 3
  Select fish that are free of white spots and have clear, intact fins. Mollies are active swimmers and are alert and curious. Avoid sluggish fish that remain at the bottom of the tank.
- 4
  Acclimate the transport bag containing your mollies to the temperature of your aquarium water for a full 20 minutes before releasing them.
- 5
  Avoid feeding mollies for the first 12 hours after introducing them into a new aquarium.
- 6
  Feed mollies a diet of flaked food. If possible supplement dry food with fresh brine shrimp or mosquito larvae occasionally.
- 7
  Observe your new fish closely for the first couple of days to make sure they are settling in well.