Magnificent mollies part 2
by Derek Lambert
Last month I dealt with the cultivated forms of molly we see regularly in aquarium shops, but what of the wild forms and where do they live? To take the last part of this question first, mollies live in such a vast range of habitats you really can’t generalise about them. The extremes include saltwater lagoons much saltier than the sea, sulphur springs where almost no other fish can survive, deep cave systems where they have adapted to a life in total darkness, and mountain lakes where a thin layer of ice can form during cold winter snaps. You name the type of habitat and I can probably find a molly living in it or in a habitat very similar to it.
These are some of the most amazing fish ever to have come out of the American continent and it has to be said, remain a thorn in the side of any ichthologist who studies them! The problem is that many species have different colour and size morphs. So the same species can look totally different depending upon its genetic make-up. Add to this the effect environment has on the fish and you really do have a complex group of fish which still needs a lot of work doing on it to sort out which are valid species and which just colour morphs or variations on a basic theme.
“Let me tell you a story”
To show you what I mean let me tell you a story. Many years ago a little molly was imported to the U.K. as Poecilia chica (chica means small and refers to the general size and finnage of this fish). These pretty little mollies were bred and produced larger more robust fish with bigger fins than the original imports. People (including myself) started to mutter that the U.K. breeder had hybridised them with other mollies to get bigger fish for the show circuit. A year or so later I decided to collect a few of these mollies myself so that we had the “pure” species in the U.K. again. This I did and my wild caught fish resembled the original imports on size, colour and finnage. I then bred from them and passed youngsters out to various people. These were duly raised up and turned out larger, better coloured and even bigger finned than the wild caught fish. Good aquarium conditions had allowed the fish to develop into much better animals than those in the wild.
Years on, and after several more visits to this part of Mexico looking at several different habitats that this species occurs in, it is now clear these fish develop very differently depending upon the habitat they grow up in. Fast flowing streams produce long slender fish. Sluggish weed filled backwaters, produce smaller deeper bodied fish. There are two colour morphs for mature males as well. One has almost black finnage and a deeper nut brown body colour that develops in alpha males. The others tend to have much less colour in the body and almost clear finnage.
Some wild species
I tend to divide wild mollies into three main groups. The Sailfins, the shortfins, and the little ones. Starting with the sailfin types, there are currently 3 species known to science. Poecilia latipinna, Poecilia veliferaand Poecilia petenensis. Of these, the first two species have been used extensively to create the cultivated sailfin mollies. However, in many ways it is the third species that has greatest potential for something new. This sailfin molly develops a short stubby sword at the bottom of its tail. Whilst this characteristic can be seen in the other two species it is best developed in this species. All three are similar in colour, being greenish with blue highlights. Poecilia latipinna and P.velifera have black speckled forms in the wild as well which are very attractive but hard to come by.
All these species tend to occur in hard, alkaline water areas and many of their habitats are brackish in nature. They require large tanks with good filtration and some water movement. It is possible for adult males of all these species to reach 4” in the wild, however, they do have smaller size morphs which are adult at only 2”. Food is important, however, only in so far as there is enough of it. These are pigs on fins and will eat all day long if given the chance. In general, they are peaceful in captivity, however, some individuals will become aggressive and bully smaller fish. Male Guppies are often a target in a community tank.
The shortfin types are where the greatest confusion reigns. Poecilia sphenops and Poecilia mexicana are the two best known species, but there are dozens of different forms of each of these depending upon where they are collected. There are also a number of species which have been listed as synonyms of these two species but are probably valid species in their own right.
Most famous of all these is the Liberty Molly. For years this was said to be a hybrid between Poecilia sphenops and Pocilia mexicana. It has now been established that it is actually a valid species in its own right,Poecilia salvatoris REGAN, 1907, and originates from Honduras, Nicaragua and Panama. One of the most beautiful forms of this species comes from San Lorenzo in Nicaragua. This strain has lovely bright red finnage with the classic black, white and red banded dorsal fin which the Liberty molly is supposed to exhibit.
The biggest species of them all, Poecilia catemaconis is said to grow up to 10” long in its natural habitat. In captivity they all remain about 3 - 4” long and the males exhibit a larger dorsal fin than the females. A particularly attractive form of Poecilia sphenops occurs at Pichucalco, Grijava, in Mexico. A few of the fish from this population have black blotches over much of their blue tinted body and lemon yellow finnage. Real stunners if you can find them.
The little ones
This group includes a number of species which really don’t fit in with the short-fin mollies. They are much smaller fish (about 2” full grown) and often come from unique habitats. Apart from Poecilia chica, two other Mexican species are worth looking out for. Both are very rare in the wild. Poecilia latipunctata originates from the Rio Mante which is fed by a warm water spring system. These little mollies require a temperature of between 78 and 84 F in captivity to thrive. Whilst not gaudy, they are attractively coloured with a silvery body with hints of blue and pale yellow finnage.
The other Mexican species to look out for is Poecilia sulphuraria. This species comes from Banus del Azufra, a sulphur spring in southern Mexico, and has proven almost impossible to maintain in captivity. In its native habitat it survives in conditions only one other species of fish can live in, Gambusia eurystoma. These two fish are found only in this spring system but in huge numbers. At times it looks like there are more fish than water and tidal waves of fish shimmer past whenever they feel a predator is near.
In this article I have just scratched the surface of wild mollies. They really are an amazing group of fish which few people outside of specialist societies have had the opportunity to keep. A few shops do sell these more unusual species but it is always wise to phone before you travel.
South America is home to a few mollies but one pretty little one worth keeping is Poecilia caucana. This comes from Columbia and is a lovely blue fish when seen in sunlight. Fully grown at just 2” this steel blue beauty is easy to keep and able to adapt to a wide range of conditions. In the wild it lives in soft, slightly acidic water conditions, which is usual for this group of fish. They eat all commercial foods and do best in a planted aquarium. They are totally peaceful and excellent fish for a community aquarium.
Keep it pure
Just about all mollies will mate with other mollies, even if they have females of their own species in the aquarium. For this reason only keep one species of molly in a tank. You can mix them with other community fish, but never with other members of the Poecilia genus.
Alpha male = The dominant male in a group.