Breeding livebearers: guppies, platies, mollies, swordtails

Livebearers breed on their own in any tank with males and females: females give birth to free-swimming fry about once a month, though the interval varies with the species and conditions (from 20 to 60 days in guppies). To raise fry, give them dense plants or moss to hide in, or move a heavily pregnant female to a separate tank and return her after the birth.

Breeding livebearers: guppies, platies, mollies, swordtails
Photo: Marrabbio2, CC BY-SA 3.0, via Wikimedia Commons

Signs of a pregnant female

A growing, boxy belly and a darkening gravid spot near the vent. Close to the birth she may hide or hover near plants.

Saving the fry

  • Dense plants, moss or floating plants give fry cover.
  • A separate small tank with a sponge filter is safer than a breeder box, which stresses some females.
  • Feed fry crushed flakes and baby brine shrimp several times a day: feeding fry.

If you do not want fry

Keep an all-male group, or plan where the young will go before they arrive; most local fish stores and clubs take healthy fry. Never release fish outdoors.

Guppy · platy · molly · swordtail