Learn about natural habitats and wild fish

   In the rainbow moth, there is an extraordinary difference in the standard length of adults in both sexes. This phenomenon is special and occurs within populations. Males are more prone to such a disproportion.
Among wild males, an incredible difference in the size of the same old fish can be found, depending on the location and climatic influences.
In Florida, USA, adult males can reach a length of 16 to 103 mm. The dorsal fins are also highly variable and reach a height of 6 to 45 mm with 10 to 17 rays (Snelson, FF, Jr. 1985).
In contrast to this type of overt sexual dimorphism, some adult small males, 30 mm or less in length, do not show characteristic secondary sexual characteristics at all. They are very similar to females and the only visible sexual characteristic is the gonopod.
Only males over 45 mm begin to show markedly the typical morphology of the phenotype, especially those special characteristics of males that can be observed in normal fish sold in small pet stores. These larger specimens begin to show traditionally exceptional coloration, and the developed dorsal fins, which can reach up to 45 mm in height, are completely different from the opposite sex. On the one hand, males in a given population are always quite small (16 to 40 mm in length), and there are no larger males. The second population, however, contains several sizes of males (18 to 60 mm in length), the smallest males are present only in small numbers (Snelson, FF, Jr. 1985). It is in this second population that we can catch large fish, especially in the summer months, which are very similar to the usual farmed aquarium form.
Probably, the characteristic differences in size between populations may be due to certain environmental parameters, social and genetic, that control such variability among males (Snelson, FF, Jr. 1985).
Unfortunately, domestic (cultivated) strains identified as Poecilia latipinna are increasingly distant from their origins and ancient wild fish, many are undoubtedly hybrids with other species of moths.
In its evolution, the rainbow moth has managed to spread to areas occupying an exceptional diversity of habitats.
These fish can still be found in both freshwater and saltwater, with some populations in coastal areas occasionally penetrating saltwater. Such flexibility encourages dispersion and invasion of new territories.
In fact, this species shows a broad tolerance for environmental factors and astonishing flexibility, such as a very low level of dissolved oxygen in water.
Due to their physiognomic characteristics, these fish can actually survive very low oxygen levels. Poecilia latipinna reduces oxygen consumption through a flattened head, superior mouth position and specially shaped lips that draw water from a thin aqueous surface film where satisfactory dissolved oxygen levels can still be achieved, in environments where most fish would die from suffocation.
Adult males shorter than 45 mm are also common in smaller populations or in those regions where cold winters are more common. Immature males born at the end of the breeding season will need more time to fully develop and will grow until next spring when they reach sexual maturity. The explanation for this size deviation was a simple biological fact. Males of the family poeciliidae grow in a noticeable way only until they reach sexual maturity. 
Sexual selection may play an important role in this evidence and in the morphological variability of the species.
Females choose males on the basis of higher dorsal fins and more pronounced body color.
It is also an individual because of greater beauty, larger dorsal fins, ... also more obvious prey of predators.
The simple fact that a female allows herself to remain in the presence of such a pronounced male during courtship can also endanger her life, as both become more noticeable to the predator.
Either way, success in mating a male doesn’t just depend on big fins and bright colors.
It is common to find more females than males in wild populations, while there is relative symmetry between the young in the sex ratio. The same can happen in captivity when there are no predators.
In the natural environment, these fish are omnivorous, with an emphasis on a vegetarian diet. They feed mainly on a variety of green matter (predominantly plant detritus, filamentous and unicellular algae), but also on almost all small prey of suitable size, such as animal benthos, zooplankton, aquatic invertebrates, insects and their larvae, including mosquitoes at all stages of development.
Domestic strains in captivity adapt to normal fish that have a normal diet.
The use of the same foods equivalent to other popular animal species is an appropriate choice, without any special supplement or meal care other than the addition of a plant substance.
It is one of those species that easily accepts commercial food in flakes. In addition to a dry, fresh or frozen diet, we must not forget vegetarian ingredients in the name of good animal health.
Occasional or frequent live prey has an amazing impact on the overall health of these fish.
Note that it is highly recommended to include artemia, mosquito larvae, small aquatic invertebrates, and other common live prey (live or frozen) in addition to several plant alternatives.

If we move north according to their geographical distribution, the local population often faces low winter temperatures. In some areas, this means a period of interruption of reproduction, because the water drops below 17 ° C, up to 14 ° C, a lot depends on what population we are talking about.
The state of Florida is considered a subtropical region, but the species has also been limited to two breeding seasons on the southern borders, one between April and June and the other between August and October.
In general, some males born in April may be ready to mate in September or October. The side effect of early sexual maturity is that these males will be mostly smaller compared to others who will only reach sexual maturity next spring between 11 and 13 months. As already mentioned, males stop growing when they reach sexual maturity.
The species in the subtropical region on the southern borders of the geographical distribution of species in Mexico, becomes fertile throughout the year.
The ideal temperature for pregnancy is between 20 ° C and 26 ° C.
The female's pregnancy lasts from 21 to 68 days. The time between litters is quite related to water temperature, salinity and diet.
Pregnancy at 29 ° C  it can take about 28 days. Above 32 ° C, complications and risks to the mother and fetus increase significantly.
Laboratory experiments have shown that salinity can become an important factor to consider. 
Salinity is also a key factor in the success of reproduction, the size of the newborn and the growth of the offspring.
According to the same source, most pups were at 25% salinity at birth (1,018). On the other hand, lower numbers are reached in both fresh and sea water - 35% salinity (1,026).
Another important piece of data resulting from this laboratory experiment is that 10% salinity (1,007) resulted in better rates of juvenile rearing (Kumaraguru Vasagam et al., 2005).
Full-grown larger females can give birth to 200 pups or even slightly more.
Cannibalistic behavior in captivity is rare, but it can occur in small aquariums or when hungry adults are present, as well as in poor fish nutrition.
The rather popular use of hatcheries is one of the most important sources of stress, often associated with pregnancy problems. Females who have been exposed to such an experience in cages will face lasting agony and suffering leading to long periods of pregnancy itself.
These unnecessarily long pregnancies are very often associated with health complications resulting from problematic births, miscarriages, and high mortality rates in newborn fish.
Successful fertilization can lead to eight consecutive litters. Females can store sperm for up to 2 years.
Feeding newborns and pups will not pose any particular problems. This species will follow the usual needs of other members of the subfamily Poeciliinae.
Newborns are relatively large. They can measure 9 to 12 mm at birth. Less than an hour after birth, they take small live prey as aquatic invertebrates of appropriate size or any other artificially common fish food.

Source: http://www.viviparos.com/