Tropical Fish: Guppy Fish

Breeding Guppies

Poecilia Reticulata Species

Guppies are livebearers, which means that every 30 days or so, the female will drop a litter of babies that are fully formed miniatures of their parents. In a community tank with other types of fish or in a tank with many adult guppies, the babies stand an excellent chance of becoming a snack for the adult fish.

If you have a lot of floating plants in the tank, some of the babies will probably survive, but if you want to maximize the number of offspring that make it, it's best to give the pregnant female her own small tank in which to give birth. A 5- or 10-gallon tank is fine.

This tank should be set up with floating spawning mops and more mops on the bottom of the tank, and/or some dense plants like Java moss, hornwort or water sprite.

Use a sponge filter and heater (if needed). The female should be added to the tank when she just begins to really show her pregnancy because moving her too close to her due date runs the risk of her dropping her babies before they are fully formed.

I prefer not to place guppies (or any livebearers) into those small plastic breeding traps because I believe they can stress out the fish. I think that the "net" breeder setups with plants or spawning mops are better, and if you cannot set up a dedicated tank, net mesh will do in a pinch.

Once they get pregnant, female guppies are almost always pregnant. Even without the presence of males, a female guppy can get pregnant with future litters by storing sperm from a single previous mating to produce a few more batches of babies. This is an attribute known as super-foetation.

The "millions fish" (an old common name for guppies) can have huge numbers of offspring in a very short period of time. Consider that a female guppy can get pregnant at 2 to 3 months of age. Each pregnancy can lead to 20 to 50 babies. These babies can themselves throw 20 to 50 more babies within two to three months, and on and on. If you do the math, you can see that pretty soon you get a lot of guppies.

Here's a word of caution about local fish store guppies: It is virtually impossible to guarantee that you will get a pure strain of guppy (ones in which the babies will all look like the parents). The females are usually young breeders that are sold after they've dropped a few batches of young. The males come from everywhere in a hatchery or wholesaler.

The fish in your local fish store have all been commingled, and to a guppy it matters not what strain or color they are - any male will mate with any female.

After a few generations of random mating, guppies will begin very quickly to revert to the wild-looking fish, and lose much of their beautiful but artificially bred tail size and color. If you want to be sure of a true strain of guppy, you will likely have to get them from breeders who advertise in fish magazines and on the Internet.

By David A. Lass. This article first appeared in the October 2004 issue of Aquarium Fish Magazine.

Compatibility: Similar sized Livebearers, Tetras, Rasboras, Rainbowfish, Dwarf Gouramis, Loaches, Plecos, and Scavenger Catfish.

Guppy Fish Care:

Most species will adapt to a range of water conditions so long as the water is clean and well aerated.

Never give your guppies more food than they can eat in 1 minute! Leftover food decomposes and pollutes the tank. If food remains uneaten, remove it. Feed your guppy a small amount 2 times during the day.

Plants should be hardy varieties such as Java Fern and Java Moss that can handle the increased hardness in the tank.

It is advisable to move a gravid female into a separate nursery tank for birthing. This should be heavily planted to shield the young from their hungry mother.