Guppy, Poecilia reticulata
Guppy, Poecilia reticulata, Female. Fish caught from a freshwater pond in Maui, Hawaii, April 2022. Length: 5.8 cm (2.3 inches). Catch, photograph and identification courtesy of Ben Cantrell, Sebastian, Florida.
Guppy, Poecilia reticulata, Female. Fish caught from a freshwater pond within the Pahrump Valley, Nevada, August 2019. Length: 5.8 cm (2.3 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
The Guppy, Poecilia reticulata, is a member of the Livebearer or Poeciliidae Family, that is also known as the Lebistes and Million Fish, and in Mexico as gupi. Globally, there are forty species in the genus Poecilia, of which six are found in Mexican freshwater systems that drain into both the Atlantic and the Pacific Oceans.
The Guppy is a small fish that has a moderately robust head and the body that is moderately compressed at the rear. Their head is depressed that has a small terminal mouth that is slightly oblique with a projecting lower jaw and a protractile upper jaw that is equipped with an outer row of large backward curved teeth and several rows of small pointed teeth. Their anal fin has 8 or 9 rays and is under the single dorsal fin origin in females and slightly behind in females and their caudal fin is rounded with a narrow base. Their dorsal fin has 7 or 8 rays, a short base, and originates behind the pelvic fins; the pectoral fins are high on the flank; their pelvic fins is set well behind the pectoral fins. They are covered with smooth scales.
The Guppy is sexually dimorphic with males being smaller than females. The males have an elongated gonopodium on their anal fins; the females have a triangular anal fin and develop a black triangle between the anal and pelvic fins when pregnant. The males are highly colored in green, blue and red in various patterns and differently shaped long tails; the females are a plain drab olive color with some fish having some color on their caudal and dorsal fins. The males reach a maximum of 3.7 cm (1.5 inches) in length; the females 6.7 cm (2.6 inches). The males reach sexual maturity in two months, the females in three. Reproduction is ovoviviparous with internal fertilization and the females having the ability to store sperm until needed. The eggs develop inside the females bodies and live birth occurs every 28 days. Litter sizes vary from 20 to 80 with the fry arriving as miniature adults and are completely independent from their parents. Each female is capable of producing 15 to 28 broods over her lifespan. The fry are subject to high levels of predation by larger fish, a variety of birds and also cannibalism by their parents. To help avoid predation they form large schools. They have life spans of up to three years.
The Guppy is primarily a freshwater fish that can be found also in brackish water at depths up to 1 m (3 feet). They inhabit warm springs, weedy ditches and canals that include highly turbid at low elevations to pristine mountain streams at high elevations. They can tolerate a wide salinity range but require fairly warm temperatures (18 – 28°C) and quiet vegetated water for survival. They feed on detritus, small insects and zooplankton.
The Guppy is straightforward identification that cannot be easily confused with any other species.
The Guppy is native to Barbados, Brazil, Colombia, Guyana, Trinidad and Tobago and Venezuela, however, due to intentional and nonintentional introductions, its popularity in the aquarium trade and its use for mosquito control the Guppy now has a global distribution and it is found in all continents except the Antarctica being now established in 69 countries outside their native range. They are exceedingly adaptable with very short reproductive cycles, sperm storage capabilities and air-breathing capacity. They were introduced to Mexico in 1971 for mosquito control purposes. Their populations and ranges quickly increased to all freshwater systems and they are currently found throughout Mexico with the exception of the central and northwest portions of the county. Their popularity as an aquarium fish also enhanced their range extensions due to aquarium releases.
From a conservation perspective the Guppy is currently considered to be of Least Concern with stable, widely distributed populations. They are utilized extensively in the ornamental aquarium trade being very easy to maintain. Releases by aquarists raising havoc of native fishes and their environments. In some locations have become highly invasive capable of quickly colonizing and quickly a nuisance pest causing ecological damage because of its ability to rapidly reproduce in high numbers. They have also been utilized as a model for the study of the effects of predation on the of morphology, behavior, and life history. They have also been used as a model for genetic research.