Signs a Guppy Is Going to Give Birth

Colorful and easy to keep, guppies are one of the most popular choices of aquarium hobbyists. Unlike most fish species, the guppy does not lay eggs. Instead, the female gives birth to live offspring, known as fry. A typical birth, which follows a gestation of 21 to 28 days, may involve 12 to 30 fry released over a few hours. The needs of mother and offspring give the home breeder a good reason to set up a suitable environment for the fish and recognize the imminent birth.

  1. Breeding Needs

    • For a guppy to become pregnant, the water temperature needs to stay at an optimum 72 degrees. Higher temperatures may lead to a shorter gestation period. Adding cover to the tank provides a place for the fry to nest just after the birth. The Breeding Guppies website recommends java moss for this function, noting that the thick plant discourages bigger guppies from reaching the newborns.

    Physical Signs

    • The most telling physical sign of a guppy about to birth is the appearance of the gravid, a dark spot at the rear of the female̵7;s abdomen. During gestation, the gravid appears larger and darker ̵1; the coloration is actually the fry eyes showing through the skin. You may even be able to make out the details of the eyes. The guppy overall appears heavier. When she is nearing delivery, the fish̵7;s birthing vent will dilate.

    Behavioral Signs

    • The farther into the gestation cycle, the heavier the guppy will become; she likely will not move around as she does normally. As she prepares to birth, she may stop moving altogether. Any causes of stress to the female could lead her to either absorb the fry into her system and not give birth at all, or to kill and eat the babies once she has delivered them. According to Interesting Animals, excess stress may also cause the female to miscarry, deliver prematurely, or sicken and die prior to delivery.

    Expert Views

    • When birthing is imminent, experts recommend removing the female from a community tank, creating hiding spaces or setting up a birthing trap in the main tank. Gardner McBride of Guppies.com, for instance, suggests installing plastic plants where the fry will hide. The Breeding Guppies site notes that a separate tank could protect the fry from tankmates that may eat the young. David A. Lass, in an ̶0;Aquarium Fish Magazine̶1; article posted on the Tropical Fish Data website, says that commercially sold breeding traps serve to stress the fish. He prefers to sequester the birthing female in a net mesh.