Guppies are highly prolific livebearers. The gestation period of guppies varies considerably, ranging from 20 to 60 days at 25 to 27.8 °C (77 to 82 °F) and depending on several environmental factors. Reproduction typically continues through the year, and the female becomes ready for conception again quickly after parturition. Male guppies, like other members of the family Poeciliidae, possess a modified tubular anal fin called the gonopodium, located directly behind the ventral fin. The gonopodium has a channel-like structure through which bundles of spermatozoa, called spermatozeugmata, are transferred to females. In courted mating, where the female shows receptive behavior following the male’s courtship display, the male briefly inserts the gonopodium into the female’s genital pore for internal fertilization. However, in the case of sneaky mating where copulation is forced, the male approaches the female and thrusts the gonopodium at the female’s urogenital pore.  Once inseminated, female guppies can store sperm in their ovaries and gonoducts, which can continue to fertilize ova up to eight months. Because of the sperm-storage mechanism, males are capable of posthumous reproduction, meaning the female mate can give birth to the male’s offspring long after the male’s death, which contributes significantly to the reproductive dynamics of the wild guppy populations.

They are approximately 2 inches long. Males are smaller than females but typically more colorful. Males have bright colors and large, ornamental fins; females are larger and plainer but may also have bright colors in some hybrid varieties. There are tons of varieties with new hybrids being created all the time.  Guppies are omnivores, eating flakes, pellets, and occasional live/frozen foods like brine shrimp. The also eat mosquito larvae, algae and other microscopic aquatic organisms.  A 10 gallon aquarium will work for a small group of guppies, but 20 gallons is better for stability and space to accommodate babies. Guppies prefer slightly hard water.

Dechlorinated freshwater with a heater and air pump, hose and air stone are necessary. A filter is recommended to purify the water of nitrate and nitrites if there are many fish in the aquarium.  Plants also assist in oxygenating and purifying the water.  Live plants and ornaments are beneficial for hiding spots, especially for fry (baby guppies) since adult guppies and other fish will eat them. Guppies are compatible with most other peaceful, similarly sized fish. Caution: Other peaceful species may eat the guppy babies.  They are prolific breeders. They breed very easily starting young and for their entire life.  The average lifespan of guppies is  2–3 years, but they can live up to 4–5 years with excellent care. Guppies are highly social, shoaling fish that should be kept in groups of at least 4 to 6 to prevent loneliness and stress.

For optimal breeding success, maintain a ratio of 1 male to every 2–3 females to minimize harassment and a minimum of 4–6 fish to satisfy their social, shoaling behavior. If using a small aquarium/container (5 Gallons): 3–4 male guppies (avoid mixing genders unless there is adequate space to accommodate the fry, as they breed rapidly). If using a (10 Gallons) aquarium/container: 5–6 guppies, or up to 10–15 with heavy planting and strong filtration.

If you are starting with a breeding group, 1 male with 2–3 females is the standard ratio, but expect rapid population growth.   A group of all-male guppies is recommended for vibrant, colorful non-stop activity without breeding.