Scientific Name: Poecilia reticulata

 Ease of Breeding: Easy

 Introduction: Imported to Europe around the turn of the last century, guppies soon earned the nickname "millions fishes," a reference to their prolific breeding habits. Although the wild form is somewhat drab, guppies have been selectively bred to create an astonishing array of colors and patterns.

 Sex Differences: Male guppies are smaller and more colorful than females.

 Water Conditions: Hardness and pH are not critical but extremes should be avoided. Temperature should be between 75° and 82°F.

 Equipment: No special equipment required for breeding, but to raise the fry, you'll need a rearing tank, or at least thick foliage in the main tank to shelter them from hungry tank-mates.

 Conditioning and Triggers: Condition together or separately with brine shrimp, white worms, and mosquito larvae plus flake food for a week or two prior to spawn­ing. Spawn in groups of one male and two or three females per male.

 Spawning: The male spreads his fins and swims around the female in an elaborate pat­tern, then repeatedly touches his gonopodium to her vent to transfer sperm. The female gives birth four to six weeks later, depending on water temperature. (The higher the temperature, the shorter the gestation.) As the pregnancy progresses, the female devel­ops a gravid spot, and when delivery is imminent, she may get a squared-off look to her belly, dart around the tank, become quieter than usual, or hide. If you plan to transfer her to a breeder's trap to give birth, do it now; if you move her too early, she may become stressed and lose her fry.

 Brood Size: There have been reports of a single female giving birth to 150 to 200 fry, but broods of 20 to 100 are more common.

 Fry Care: Baby guppies are coiled inside a membrane at birth, but immediately break free and swim toward the nearest light source, making them easy to net for transfer to a grow-out tank. If they'll remain in the main tank, provide plenty of hiding places, such as floating plants, to protect them from other fish. Feed liquid or powdered fry food for­mulated for livebearers, baby brine shrimp, and or flake food crushed into powder. Guppies are capable of reproducing when they're only two months old, so if you don't want more fry, separate the sexes.