guppy

Guppy
Male guppy
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Cyprinodontiformes
Family:	Poeciliidae
Genus:	Poecilia
Species:	P. reticulata
Binomial name
Poecilia reticulata Peters, 1859
Synonyms
Acanthocephalus guppii A. reticulatus Girardinus guppii G. petersi G. poeciloides G. reticulatus Haridichthys reticulatus Heterandria guppyi Lebistes poecilioides L. reticulatus Poecilia poeciloides Poecilioides reticulatus

The guppy (Poecilia reticulata), also known as the millionfish,^[1] is one of the most popular freshwater aquarium fish species in the world. It is a small member of the Poeciliidae family (females 4–6 centimetres (1.6–2.4 in) long, males 2.5–3.5 centimetres (1.0–1.4 in) long) and like all other members of the family, is live-bearing.

Taxonomy

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. Günther 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.

Over time guppies have been given a variety of taxonomic names, although Poecilia reticulata is the name currently considered to be valid.^[2]

Distribution

Guppies are native to Barbados, Brazil, Guyana, Netherlands Antilles, Trinidad and Tobago, the US Virgin Islands, Venezuela.^[3]

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.^[4]

Ecology and behavior

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 colour, 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. This makes the selectively bred guppy not as hardy as the wild guppy, therefore, a guppy may not survive a sudden increase or drop in temperature.

Reproduction

A pregnant guppy at about 26 days

A baby guppy in an aquarium at 1 week old

Guppy standards

Guppies are highly prolific livebearers.^[5] 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 (81 °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. If not kept separate the older, mature guppies will eat the fry so the use of a breeder box, net breeder, or a 5–10 US gallons (19–38 l; 4.2–8.3 imp gal) tank is recommended.

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.^[6] The guppy has also been hybridised with the Endler's livebearer (poecilia wingei) to produce fertile offspring. The adult guppies sometimes eat their fry; owners may use a breeder cage to prevent this.

Genetic

Guppies have 23 paired chromosomes including 1 pair of sex chromosomes.^[7] The most dominant gene in a guppy is the wildtype gene.

In the aquarium

The guppy prefers a hard water aquarium and can withstand levels of salinity up to 150% that of normal sea water,^[8] which has led to them being occasionally included in marine tropical community tanks, as well as in freshwater tropical tanks. Guppies are generally peaceful, though nipping behaviour is sometimes exhibited between male guppies or towards other top swimmers like platys and swordtails and occasionally other fish with prominent fins such as angelfish. Its most famous characteristic is its propensity for breeding, and it can breed in both fresh water and marine aquariums.^[9]

Selective breeding has created the "fancy guppy" due to the mutations that occur in each generation.^[10] Guppies bred by aquarists produced variations in appearance ranging from colour consistency to various tail forms.

Well fed adults often do not eat their own young, although sometimes safe zones are required for the fry. Specially designed livebearer birthing tanks, which can be suspended inside the aquarium, are available from aquatic retailers. These serve the dual purpose of shielding the pregnant female from further attention from the males, which is important because the males will sometimes attack the females while they are giving birth. It also provides a separate area for the newborn young as protection from being eaten by their mother. However, if a female is put in the breeder box too early it may cause her to have a miscarriage. Well planted tanks that offer a lot of barriers to adult guppies will shelter the young quite well. Java moss, Duckweed (Lemna minor), and Water Wisteria are all excellent choices.

References

Further reading

• Houde, Anne E (1997). Sex, Color, and Mate Choice in Guppies. Princeton, NJ: Princeton University Press. p. 227. ISBN 0691027897. 

External links

Wikimedia Commons has media related to: Poecilia reticulata

• Poecilia reticulata (TSN 165903). Integrated Taxonomic Information System. Retrieved on June 8 2004.
• "Poecilia reticulata". FishBase. Ed. Ranier Froese and Daniel Pauly. April 2004 version. N.p.: FishBase, 2004.