Separating Pregnant Guppies

Guppies are one of the most proliferate fresh water fish you can buy. Most female guppies breed every 30 days and can give live birth to as many as 200 fry in a single liter. In large tanks it̵7;s possible for multiple guppies to be pregnant at the same time. Separating pregnant guppies from each other and from other community fish is necessary to ensure fry grow into adult guppies, rather than become food for mom or other tank-mates.

  1. Determine Gestation

    • Female guppies gestate for approximately 28 days. During the final stages of pregnancy, the mother̵7;s underbelly will become distended and somewhat squared off at the bottom. Imminent birth is characterized by the dark mass in her lower belly near the tail called the gravid spot. The dark color is the eyes of the multiple fry about to be born. Place pregnant guppies in a separated breeder tank as soon as the belly begins to square off, at approximately 25 days of gestation.

    Breeder Tanks

    • Breeder tanks are specially-designed boxes separated into four or more sections. The tanks float inside the main tank, yet keep pregnant guppies separated from the other fish and keep the newborn fry separated from their mothers. Average tanks have two separated upper compartments that can each accommodate a single pregnant guppy. These tanks are then subdivided into two other smaller tanks below by a slotted piece of plastic. When fry are born, they drop through the mother̵7;s tank into a separate, angled-slot tank of their own. This physical separation keeps them from being eaten by their mother.

    Length of Separation

    • Guppies can give birth to a single liter of fry over the period of a few hours, or even a few days. Because of this phenomenon, leave the mother in her isolation tank for at least 48 hours, until her abdomen has shrunk back to its normal pre-pregnancy state. At this point, you can return her to the community tank. Fry should stay in their separated compartment for at least 25 days, or until they are large enough to survive among larger fish. At this point you can put them into a tank of their own or into a community tank, provided there are plenty of plants to serve as hiding spots.

    Mixing Fry Generations

    • If you are breeding many guppies simultaneously, you will need more than one breeder tank, or at the very least, a breeder tank with compartments for multiple females and fry groups. If you mix fry generations, placing a pregnant female into a fry-occupied breeding tank and allowing newly born fry to fall into the compartment with larger fry, the larger guppies are prone to eat the smaller ones.