Molly fish care for beginners

Mollies are hardy, friendly livebearers that come in black, white, orange, dalmatian and balloon shapes. They're easy to keep, but they grow bigger than most beginners expect and they like harder water. Here's what they need.

Molly fish facts

• Size: 3 to 4 inches, and sailfin mollies can reach 5
• Tank: 30 gallons or more
• Temperature: 72–80°F
• Water: hard water with a pH of about 7.5 to 8.5
• Group: 3 or more, with more females than males
• Lifespan: about 3 to 5 years

Do mollies need salt?

No. Wild mollies can live in slightly salty water, and that's why some stores recommend salt. Mollies sold today do well in ordinary freshwater, as long as it's on the hard side with a pH above 7. If your tap water is very soft, crushed coral in the filter or substrate raises the hardness gently. Salt also harms many tankmates, such as corydoras, so skip it.

Males, females and babies

• Telling them apart: males have a pointed fin under the belly called a gonopodium. Females have a fan-shaped fin there and a rounder body.
• Keep more females than males, about one male to two or three females. Males chase females constantly, and a lone female gets worn out.
• Babies are almost certain if you keep both. Mollies give birth to live young about every month or two, and females can store sperm, so a new female may already be pregnant. Plenty of plants let some fry survive. If you don't want babies, keep only males or only females.

Feeding mollies

Mollies graze on algae and need some greens. Feed a quality flake or small pellet once or twice a day, and add a vegetable-based food or blanched zucchini or spinach a few times a week. See the best fish food for beginners.

Tankmates

• Good: platies, swordtails, corydoras, bristlenose plecos, peaceful tetras and rasboras, and snails.
• Avoid: fin nippers, aggressive cichlids, and fish that need soft acidic water. Guppies can work, but mollies may nip their long fins.

Common molly problems

• Shimmying, a fish wobbling in place without swimming forward, usually means poor or too-soft water. Test the water and do a water change.
• Clamped fins and hiding often come from a male chasing too much. Add more females, or more plants to break up the view.
• White spots are ich. See ich: white spots on fish.
• A crowded tank happens fast with babies. Use the free stocking calculator to keep track.

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