How to breed guppies: a beginner's guide

Guppies breed so easily that the hard part is usually stopping them. Females give birth to live, free-swimming babies about once a month. If you want more of those babies to survive, or want to breed for color, a few simple steps make a big difference.

I've bred guppies in my own tanks, and they're the best fish to start with.

The basics

• Livebearers: guppies give birth to swimming fry instead of laying eggs.
• Pregnancy: about 21 to 30 days, and 20 to 50 fry is common, with young females having fewer.
• Females store sperm, so a female can have several batches of fry without a male.
• Ratio: one male to two or three females, so the males don't wear one female out.
• Temperature: 76–80°F speeds up breeding and growth.

Is my guppy pregnant?

A pregnant female gets a rounder belly and a dark patch near the back of her belly, called the gravid spot. As birth gets close, her belly looks boxy from the side, and you may see the fry's eyes through the gravid spot. She may hide, stop eating or hover near the heater or the surface.

Saving the fry

Adult guppies, including the mother, eat their own fry. You have three choices:

1. Lots of plants. Java moss, hornwort and floating plants give fry places to hide. Some always survive, with no work from you. See easy aquarium plants.
2. A breeder box. Move the female in a day or two before birth, then put her back as soon as she's done. Long stays stress her.
3. A separate fry tank. A 5 or 10 gallon with a sponge filter and a heater is the best way to raise many fry. See the 5 gallon tank guide.

Feeding guppy fry

• Baby brine shrimp are the best food, and fry grow fast on them.
• Finely crushed flake or fry powder works too.
• Feed small amounts 3 to 5 times a day for the first few weeks, and keep the water clean with small, frequent water changes.

Growing up

You can tell males from females at about 4 to 6 weeks: males get color and a pointed anal fin. Separate males and females by about 2 months if you want to control who breeds with whom, or to stop the tank filling up.

Breeding for color

To keep a strain looking its best, pick the best male and two or three of the best females, and raise their fry on their own. Keep the best young fish from each generation and move the rest on. Mixing many kinds of guppies together usually ends in plain, mixed-color fish within a few generations.

Too many guppies?

• Keep only males, which are the most colorful anyway.
• Add a few peaceful fish that eat fry, if your tank is big enough.
• Ask your local fish store if they take healthy home-bred fish.

Watch your stocking as numbers grow with the stocking calculator.

Related: Guppy care · Swordtail care · Platy care · Breeding aquarium fish