How to Breed Freshwater Guppies

Purchase large fish tanks and all the necessary equipment to filter and aerate them. Five- or 10-gallon tanks are suitable. Have at least one breeder tank to keep pregnant guppies in. Clean the tanks and fill with clear water and additives suggested by your fish tank dealer, then allow the tank to condition for a week before adding the fish. You can add plants to the main tank, but breeder tanks are often left unadorned.

Check the pH of the water in the various tanks using a pH kit, as they need to be identical when moving fish between tanks. The best pH for guppies is 6.6 to 6.8. Keep the temperature and conditions as close as possible to that of the breeder you purchase the fish from. Using a thermostat, keep temperatures between 78 degrees to 82 degrees Fahrenheit for guppies.

Choose the breeding stock from a reputable guppy breeder. Decide on the colors of the fish you want to breed, and select healthy looking fish, including young males and trim females. The number of fish you purchase will vary depending on your objectives. You may be purchasing fish that have already become impregnated by your least favorite-colored fish, so be sure to have enough in number to assure you get good outcomes from the colors you prefer. It's hard to tell if a fish is pregnant until their underbellies start really rounding out and appear full.

Introduce the fish to your main tank. Expect some of them to experience moderate shock, which can occur whenever fish are transferred. If any of them seem lethargic or begin to have odd-looking skin problems, remove the fish and separate them to determine what's wrong. There are many different signs of shock stages and diseases, so it's best if you consult your local fish shop or find a book specifically on guppies. Keep a close eye on the tank, especially the first few hours and days, to keep temperature, pH, and chemicals balanced and healthy.

Move the pregnant females to the breeding tanks after about 18 to 20 days. Make sure to also move about 50 percent of the water from the initial tank that the female has been used to, and restore water to the original tank. You'll easily be able to tell the pregnant fish, especially by the full bellies and black spots showing through. When pregnant, they have a dark spot at the rear of the abdoment -- this is the eyes of baby guppies showing through the female's skin. The darker the spot, the closer the babies are to birth. Babies can arrive as early as 20 or 21 days into gestation. The usual gestation period is approximately 28 days.

Remove the female after she has dropped the fry. You'll either witness the birthing or see the fry and their egg sacs at the bottom of the tank until they start swimming around. You may get anywhere from five to 50 fry from each pregnant female. Place the female into a separate tank or re-introduce her to the initial tank. Smash up flake food into a powder and feed it to the fry every day. Continue to watch the fry, introducing them to larger tanks as they grow. Add additional tanks for the numbers of fish you plan to breed and raise.