Care: Feed with vegetable-based flakes and algae. Don't clean algae off back glass, as mollies need algae for survival. Many plants and some salt in the water will do the fish well. They will be better off in brackish water, especially black mollies. Primarily a vegetarian but will accept most aquarium foods. Mollies are good algae eaters, somewhat piggish.
Breeding: Mollies are livebearers. Although they are harder to breed than Swordtails and Guppies, their breeding is still prolific. Babies will feed on zucchini cut into cubes. Some salt in the water will help with breeding, increase growth rates, and add more colour. The female will drop live fry in intervals of between 4 and 6 weeks. Fry can be raised in the same tank with parents as long as no other species of fry eating fish are present. The gestation period of mollies is 28 days.
Sex: Sex can be determined by the male's modified anal fin (gonopodium). That is the main way to tell the difference between male and female. There is no size difference, and the only way to tell is to look behind the tail fin. If there is an organ that looks like a stick or straw, it is a male, if it's a fin, it's female. The sex of the fry shouldn't be determined, becuase they all look like females in the beginnning, and they either stay female or change to male, time will tell.
Temp: 75 - 82 degreesF (25 - 28C)
Babies: Babies need a tank that is at least 10 gallons, or they won't grow at a normal rate.
Comments from a few experts:
What's recommened for the amount of salt is 1 teaspoon per 5 gallons of water.
For every male there should be 2-3 females. If there is only one female, the male will constantly inpregnate her and stress her out. When a female is separated from a male she will impregnate herself up to three times. The female black mollies store sperm inside of themselves for this reason. If you don't have many other fish, don't worry about removing a pregnant female from your tank. Live plants will help her with her birth. Females tend to choose mates that are smaller compared to themselves. If you do plan to breed mollies, or any other live-bearing fish and want to in succession, always have more than one tank. One tank can be a maternity ward, one a tank for babies and so on.
Mollies like it warm (78-80F) and salty. I used marine salt, 1 tsp./ 5 gallons, for my molly/cichlid tanks. That's not all that salty but it seems to keep them happy (they spawn, an occasional fry makes it to adulthood, they're never ill).
A 2.5 gallon hex is a lousy tank - it has the surface area of a teacup. Get them a bigger tank, like a 5, normal dimensions. You can put a small submersible heater (I like Ebo-Jagers) in it, along with a home-made breeding grate. To make the grate, use aquarium-safe silicone sealant and glue two strips of cear plastic corner molding to each long side, about 1/2 way up. After two days, you can rest a piece of fluorescent egg-crate grating on it. Put in a sponge filter that's been aged in an existing tank. Put in a bunch of scrufy java moss below the egg crate. Insert molly pair. Stand back. The egg crate prevents the parents from getting the babies. Wait until they've spawned, and you can remove the parents and grate and have a good rearing tank. Don't forget the salt!
Females about to give birth can be recognized by their round, tight stomachs, which late in pregnancy become squarish in shape. Black mollies can be identified easily by a white spot behind their pelvic fin; others by a black spot (the gravid spot). Personally I find the commercial breeding traps ideal for the pregnant female. If placed too late in pregnancy, the female can die and the fry can be damaged. A small separate glass or plastic tank with plenty of hiding places also can be used. In this way the female can be placed a week or more before giving birth. The female would be too tired to start chasing her fry immediately and she can be distracted from doing so by feeding her. Unless exceptionally predacious, the female can be given a day or two of rest in this tank.
