Learn about natural habitats and wild fish
 

  In a large area, we find wild populations of Poecilia sphenops, stretching from the Pacific coast of Mexico and the Atlantic coastline, which runs through much of Central America between Mexico and Panama and some border regions of South America in northern Colombia.

Some sources also suggest the extension of this area to Venezuela, but this may be due to confusion with other species in addition to the populations introduced by man in different areas of this country.

This moth is found in several species of ecosystems, so its variability over time can also be explained as an evolutionary adaptation to these different environments.

In coastal areas with low altitude, however, the abundance of the species is higher, although they are also found in inland environments.

One of the factors influencing its geographical distribution is temperature. Poecilia sphenops is common in environments where the temperature range is between 18ºC and 28ºC throughout the year (although some specimens survive extremes that exceed these limits).

In addition to finding large numbers of individuals in estuarine environments or mangrove ecosystems typical of the coast, there are also populations that occur at sea for at least part of the year and others that typically encourage small seasonal migrations that lead them into the ocean.

High resistance to salinity is also common, even in those individuals who come from inland rivers and lakes.

Some groups have also been found to exist in unusual nearby subterranean environments, locally known as "cenote", or in waters that are not suitable for most other species due to their chemical properties.

Malcom S. Gordon and Donn Eric Rosen in their scientific paper entitled "Caverniculous form of Poeciliid Fish, Poecilia sphenops, from Tabasco, Mexico", 1962 describe a very rare population found in extreme environments.

In the article, it can be read that specimens found in a groundwater cave are almost depigmented, have very small eyes, and more pronounced lips than those in surface environments. While they went backwards in certain peculiarities, these extraordinary specimens developed certain senses and qualities that allowed them to adapt in such a difficult environment.

As we move away from the entrance to the cave, the groups show different dimensions in adulthood, further noting the characteristics described as a result of adapting to an environment that is largely characterized by a complete absence of light.

This discovery followed an expedition carried out in 1944 by dr. MW Stirling of the Office of American Ethnology Simthsonian Institution and his wife. The couple was also accompanied by Mr. RH Stewart of the National Geographic Society.

Not far from Tapiulapa in the interior of the Cueva del Azufre (Cueva de la Sardina, Cueva de las Sardinas or Cueva de Villa Luz), this expedition group found a population of small pale fish, similar to others outside, leading to the discovery of the first wild cavefish . Preserved specimens will later be dr. Robert R. Miller of the "American National Museum" identified him as a member of the genus Mollinesia.

In 1964, C. Kosswig, N. Peters, and CD Zander collected the first fish to date, classified as Poecilia sphenops, brought to the laboratory, and even allowed the first behavioral studies.

Something​​ collections of preserved and live fish were later collected from other caves. Of these missions, we know examples of those reported in 1970, 1975, 1982 and 1996, among the various "in situ" observation missions carried out between 1970 and 2000.

It is a species that demonstrates high tolerance to environmental factors and flexibility.

Prior to the spread caused by human action, populations that were perfectly adapted to living in freshwater and brackish water could be found, and occasionally some populations that had access to the sea penetrated the ocean.

Like most species of the subfamily Poeciliinae, these moths choose shallow areas as their preferred environment, very often inhabiting small watercourses or the edges of larger bodies of water.

Because fish are not well trained to live in strong currents, they can penetrate up the water, especially during the dry season when there are no floods.

Usually, larger groups of females form in the wild, devoting themselves to feeding, while males compete with each other for access to females.

Unlike species with large dorsal fins, there are no complicated pre-mating rituals of males in this species.

Mating is always initiated by males seeking happiness in females who are most receptive to their purposes.

Many larger males defend the territory, and smaller ones try their luck by sneaking up on females.

All, without exception, respond to the resistance offered by females by force.

In the wild, the prayer is constantly multiplying every year in most of its geographical distribution. This continuous cycle is interrupted only by very special situations, which are usually associated with natural disasters or unusually adverse weather conditions. The type and amount of food also affects the distribution of the species.

  In places where the daily and annual temperature ranges are small, between the rainy and dry seasons, fish achieve an almost uniform amount of food, although they may change their diet according to the time of year.

Larger seasonal differences in available food and type of food consumed tend to occur in regions with greater temperature changes.

Moths mostly eat aquatic insects (namely Coleoptera-beetles, Diptera-biplanes, Hemiptera-half-wings, Odonata-dragonflies, Plecoptera-willows)  and Trichoptera-juveniles), plant fragments, leaves, fruits or seeds of some terrestrial plants from flooded forest, algae and microalgae, some (rare) aquatic plants, as well as some other insects (Coleoptera-beetles, Diptera-biplanes, Hymenoptera-leatherbacks and occasionally Arachnida-spiders).

In general, aquatic insects account for a slightly higher percentage than algae found in the stomachs of wild animals caught between November and April (dry season), while between May and October the plant matter consists of parts of terrestrial plants, their fruits or seeds combined with terrestrial insects they represent the largest proportion of digested food in the collected samples.

In captivity, we do not forget about dietary supplements such as overcooked spinach and peas (peeled) or one of the usual commercial foods for herbivorous species.

The average number of offspring ranges between 10 and 80, in the first pregnancy it is only 7 or 8, and in extremely large females living in very favorable conditions, it exceeds 120.

Newborns are much larger than the offspring of spawning fish, so they are not difficult to raise. Regardless of the greater or lesser amount of algae in their diet given to adults, it is advisable to add shrimp and fleas of appropriate sizes to them in addition to any dietary supplements.

If the female is adequately protected from stress and in ideal conditions, the pregnancy lasts from 28 to 45 days, depending on temperature, water quality, available food and even other lesser known factors. 

In unfavorable conditions, childbirth can be postponed for several months.

Too small aquariums, hatcheries and living with aggressive species are the three most important factors that can affect long periods of pregnancy. Inadequate temperatures and an unbalanced diet are also very important conditions in postponing childbirth.

Keeping these fish in saltwater aquariums or using sea salt is not mandatory, and the dependence on salinity depends on the original population.

Since the origin of animals normally sold in the store cannot be detected (especially since most hybrids), salinity can be left to the discretion of each individual according to the animal’s behavior.

However, salinity must change during the year, but above all it reduces the possible osmotic stress that some specimens (or even whole groups) show in discomfort or are very often attacked by mold (in fresh water).

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