Mollies
Now to one of the more spectacular members of this family, the sailfin molly. There are three species of sailfin molly of which two are common in the hobby, Poecilia latipinna and Poecilia veli-fera. As with the cultivated platies and sword tails, they have been hybridized over the years to develop more colour varieties. They like hard, alkaline water: but failing this a little salt can be added. About a level 5 ml spoonful (1 level tsp) per 4.5 litres (1 gallon) is sufficient, though they will tolerate a lot more. Indeed, sailfins are at their best in brackish to marine conditions, and marine aquarists often use mollies to mature new systems. Before adding salt to your community it is vital to ensure that the other fishes and plants will tolerate it. If not, then set up a special tank for your mollies.
Poecilia latipinna is native to the southern USA and down into Mexico, and tolerates lower temperatures than are considered normal for “tropical” fishes (20- 24°C/ 68-77°F). It is best to keep the cultivated forms at the upper end of this range. There are several colour varieties, for example, gold, black, and albino. The wild form is greenish with iridescent spangles on its flanks, but specimens with black speckling are also found, and it was from these that the black molly forms were developed. Males are clearly distinguishable by their gonopodium and majestic dorsal fin. When courting a female, the male flashes his fin up and down to attract her attention.
Fry are produced every four to five weeks. Move the female to a special aquarium, with thickets of fine-leaved and floating plants, to give birth, after which she can be removed. Poecilia salvatoris (Liberty molly) (for many years thought to be a form of Poecilia sphenops), occurs in Guatemala and Belize. Not often seen, it is a beautiful fish with red, black, and white dorsal and caudal fins. It is hardier than the sailfin types and will tolerate soft water without the addition of salt.
The black molly is the result of crossing a black form of Poecilia latipinna with Poecilia sphenops. This popular hybrid comes in several varieties including the lyretail and the balloon.
Maintaining Mollies
Mollies are easy to keep provided you maintain good conditions. If water quality deteriorates, the temperature is too low, or there is a combination of these factors, mollies are often the first to show signs of distress, for example fins clamped to their bodies while they move listlessly or even rest on the bottom or “shimmy” on the spot. If the temperature turns out to be correct, then a partial water change will usually rectify the problem.
Like other Poeciliids, mollies are true omnivores, eating just about anything which comes along. It is often recommended to add plenty of green food to their diet, and some people even suggest that it is difficult to maintain them in really good health without it. This, however, is simply not the case. Many specialist molly breeders feed no additional vegetable matter but nevertheless successfully breed and raise thousands to adult size. Mollies will browse on lettuce, peas, algae, and soft-leaved aquarium plants when nothing better is available, but this is because they are hungry all the time. Live foods such as Daphnia, bloodworm, and mosquito larvae are consumed with relish, as are minced fish and frozen foods. Feed as often as possible to obtain the best growth rates.