Robert John Lechmere Guppy discovered this tiny fish in Trinidad in 1866, and the fish was named Girardinus guppii in his honour by Albert C. L. G. Gunther later that year. However, the fish had previously been described in America. Although Girardinus guppii is now considered a junior synonym of Poecilia reticulata, the common name "guppy" still remains. (In Trinidad and Tobago, the common name is "crayfish".) Over time guppies have been given a variety of taxonomic names, although Poecilia reticulata is the name currently considered to be valid.
Guppies are native to Barbados, Brazil, Guyana, Netherlands Antilles, Trinidad and Tobago, the US Virgin Islands, Venezuela.
However, guppies have been introduced to many different countries on all continents, except Antarctica. Sometimes this has occurred accidentally, but most often as a means of mosquito control, the hope being that the guppies would eat the mosquito larvae slowing down the spread of malaria. In many cases, these guppies have had a negative impact on native fish faunas.
Guppies exhibit sexual dimorphism. While wild-type females are grey in body colour, males have splashes, spots, or stripes that can be yellow, orange, blue, red, black, or even purple.
Guppies are often bred for their natural color, so over the years the domestic guppy has grown weaker. As a result, guppies will sometimes die after 2-3 days after stress or pH shift. A guppy may not survive a sudden increase or drop in temperature.
There is a great deal of variety between the populations, many with distinctive coloring or patterning. Those that live in habitats where predators are common tend to be less vividly decorated due to natural selection. Populations that deal with fewer predators are much more colorful. Recent studies suggest that vividly colored males are favored via sexual selection (handicap principle) while natural selection via predation favors subdued tones. As a result, the dominant phenotypes observed within a reproductively isolated community are a function of the relative importance each factor has in a particular environment.
Occasionally male guppies may behave aggressively towards each other, engaging in fin-nipping and other bullying behaviour. Guppies live in complex social networks, choosing social partners and remembering them.
Guppies are a seminal species for evolutionary biologists because predation often varies over small geographic areas. Both historical work and recent studies are summarised in Anne Magurran's Evolutionary Ecology: the Trinidadian Guppy. Guppies are highly prolific livebearers. The gestation period of a guppy is 21-30 days, with an average of 28 days, varying according to water temperature. After the female guppy is inseminated, a dark area near the anus, known as the gravid spot, will enlarge and darken. Just before birth, the eyes of fry may be seen through the translucent skin in this area. Guppies prefer water temperatures of about 27 °C (82 °F) for reproduction. The female guppy has drops of between 2-100 fry, typically ranging between 5 and 30. From the moment of birth, each fry is fully capable of swimming, eating, and avoiding danger. After giving birth, the female is ready for conception again within only a few hours. In fact, guppies have the ability to store sperm, so the females can give birth many times, after only once breeding with a male. Also If moved too early your Guppy may give birth to a small amount of fry(An Average Of 12). Young fry take roughly one or two months to reach maturity. In the aquarium, they are usually fed ground flake foods, baby brine shrimp or unless they are put in a separate tank, the babies will eat uneaten food from the adults. In addition, they nibble on algae. The guppy has been successfully hybridised with various species of molly (poecilia latipinna/velifera), eg male guppy and female molly. However, the hybrids are always males and appear to be infertile. The guppy has also been hybridised with the Endler's livebearer (poecilia wingei) to produce fertile offspring. The adult guppies sometimes eat their fry; some breeders use a breeder cage to prevent this.