Mating Habits of Guppies

Originally from the fresh and salty waters of Central and South America, the guppy (Poecilia libestes reticulata) is a small fish that can now be found in the wild in many parts of the world. The guppy is a popular aquarium fish since it is low-maintenance and generally not aggressive, although male guppies sometimes mate with female guppies by force. Guppies are live-bearers, which means that they give birth to live, free swimming young instead of laying eggs.

  1. Sexual Maturation

    • The rate at which a guppy sexually matures depends on a number of factors. Male guppies can sexually mature a few weeks after birth while female guppies mature at about 3 months. Water temperature and availability of food can speed up the usual rate of sexual maturity. Higher water temperatures increase the guppy's metabolism, causing it to eat more of whatever food there is and grow faster. A sexually mature male has a gonopodium, an anal fin that it uses to impregnate females.

    Attraction

    • Besides being smaller, male guppies are more colorful than female guppies. While male guppies come in many patterns, they all usually have one or more spots and have bright splashes of color. Some male guppies from Trinidad have orange or yellow coloring with black stripes and dots. Further south in Brazil, male guppies can have blue and purple metallic coloring with two big dots. In contrast, female guppies are a drab silver or gray. Male guppies are more colorful because they need to attract females to mate with and pass on their genes. Scientists believe that female guppies are attracted to colorful males because flashy male guppies simply draw more attention. Female guppies also may regard colorful males as more healthy, which gives any young from the union a better chance at survival.

    Mating

    • Male guppies advertise themselves to females by contorting their bodies into an "S" shape, spreading their caudal and dorsal fins and shaking. When it wants to mate, the female guppy will move slowly toward the male that it has chosen. The male then approaches the female, places its gonopodium toward the female's gonopore and transfers its sperm. Sometimes, a male inseminates a female by force by sneaking up to her and touching its gonopodium to her gonopore. Both males and females mate with multiple partners.

    Reproduction

    • An inseminated female guppy can store the sperm in her body for a long time afterward, allowing her to get pregnant multiple times after mating once. For this reason, a female guppy purchased at a pet store can later give birth even when placed in an aquarium without any males. Since the female mates with multiple partners and stores their sperm, one brood of young can be have both full and half-siblings.