Guppies 

Pretty Little Fish Food 

Poecilia reticulata

Next to Goldfish Carassius aureatus, Guppies are the most widely kept pet fish and by far the most popular tropical tank species. They are also prolifically bred and raised by amateurs and professionals alike. The Guppies do all of the work in a breeding program preferring it even above eating. If not watched and proper steps are not taken to intervene, Guppies will overpopulate a 10 gallon tank in a matter of months "just doin' what comes 'natcherly'." Females may produce a litter of 2 to 100 fry every four weeks. The popular name dates to 1859 when an explorer and biologist named Robert John Lechmere Guppy sent a few living pairs from Guyana to the British Museum in London, England. Since that time this diminutive fish has been commonly called by the explorer's name. The Guppy was widely known as Lebistes reticulatus until 1963 when the taxonomic name Poecilia reticulata was substituted.

The Poecilia reticulata naturally inhabit slow moving streams and shallow lakes in the waterways of Northern Brazil, Guyana, Venezuela, Barbados and Trinidad. They are one of the many live-bearing toothcarp species indigenous to the tropical new world from southern North America, including the West Indies, south to Northern Argentina. The male Guppies are equipped with a special organ called the gonopodium. The third, fourth and fifth rays of its ventral fin form a trough. During mating the trough is closed to form a tube by the ventral fin and is inserted into the oviduct of the female. Tiny packets of sperm pass through the tube into the female where some of them dissolve, releasing the sperm to fertilize ripe eggs. Other packets of sperm are "stored" in folds of the oviduct wall and may be used by the female, in the absence of a viable male, to fertilize future batches of ripe eggs for a period of up to four months. The eggs are comparatively yolky and provide all required nourishment to the embryos. Following a gestation period of four weeks the fry (immature fish) emerge live from the female and are usually capable of free-swimming and eating within one hour.

Male Guppies come in a profusion of colors, with numerous possible tail and fin shapes and sizes. The females are always duller and less interesting looking than their male counterparts, often of a single solid color. Males are always much smaller than females from the same breeding source. The markings of the different varieties form a limitless array of patterns and mosaics. The colors in Poecilia reticulata can be caused by deposition of pigment or by the presence of reflective guanin beneath the scales and all combinations of the two. Even wild fish taken from natural surroundings exhibit an amazing variety of color schemes, marking patterns and tail shapes. Some of the more commonly known tail (caudal fin) shapes include roundtail, cofertail, pintail, spadetail, single and double swordtail, lyretail, speartail, scarftail and fantail. Coloration and caudal fin shapes of guppies can be closely controlled in a captive breeding program by carefully selecting breeding pairs and timely segregation of offspring from parents and opposite gender siblings. These same precautions are required to prevent cannibalism of the fry by mature fish.

Poecilia reticulata is extremely easy to care for in the home or office with a minimum of equipment and knowledge. As with any endeavor, added knowledge and more sophisticated equipment will increase the hobbyist's enjoyment commensurately. While the recommended water temperature range is 73° to 83°F, they are quite capable of surviving in an unheated (room temperature) aquarium or container. Lower temperatures may shorten their life expectancy and stunt their maximum size potential. Temperature is also critical in maximizing production of offspring. They are tolerant of a fairly wide range of water hardness and pH values, but are best suited to a pH range of 6.8 to 7.6 (7.0 to 7.2 being ideal), and a DH of 4 to 10. Do not add salt. It is unnecessary and may harm some fish.

Adequate light is vital to health and plays an indispensable part in the mating process. Female Guppies are very visually selective of males with whom they will breed. The minimum light requirement is 10 to 16 hours per day with corresponding periods of darkness. It is most desirable to have at least a few floating plants in the tank as they will assist in the transpiration of unwanted nitrogen compounds dissolved in the water. These compounds accumulate as the fish respirate water through their gills. With or without plants, partial water changes at least once a month are essential. Remove at least 10% of the water and replace it with conditioned (dechlorinated and temperature adjusted) water. The water should be filtered using an undergravel filter or marbles and floss. External filters must be fitted with sponge covers on the intakes to avoid sucking up the Guppies. Acivated charcoal will remove gasses and unpleasant odors from the water.

Guppies must be fed at least once and may be fed twice or more daily. All-purpose tropical flakes will suffice as a total diet if the fish are merely kept as pets. If maximization of body size, intensity of color and brood proliferation are concerns, include bloodworms, brine shrimp, rotifers and beef heart paste in their diet. Brine shrimp and rotifers are only needed by fry during the first three or four months of life, and beef heart paste should only be fed just prior to water changes since it has a tendency to cloud the water. Bloodworms may be fed live or frozen. If frozen, thaw first in a small amount of tank water then add back to the aquarium. The Guppies enjoy bloodworms so well they will try to fill their mouth with more than will fit, and they will chase eachother around trying to steal worms from their tankmates.

Laurel Lake Guppy Hatchery

Copyright © 1997 Gary Churchman
This page was created Friday, March 14, 1997
Most recent revision Wednesday, July 2, 1997