Guppy ( Poecilia )

Guppies (Poecilia reticulata) are native to Trinidad and northeastern South America. The guppy is a popular study organism among biologists because it is characterized by wide variation in behaviour, life history characters and appearance. Aquarium fish hobbyists have long been interested in the many colours male guppies can take, and breeders have produced different guppy lines in the same way that dog breeders have produced poodles, retrievers and terriers. Guppies in their natural environment look and behave much differently than guppies found in most pet stores.

Some differences between natural and store-bought guppies:

1. Male and female store-bought fish are often the same size. Natural male guppies are smaller and have a narrower abdomen than females.

2. Female store-bought fish are often colourful. Natural female guppies are drab and cryptic against light-coloured backgrounds. Natural males are very colourful (especially orange), but the colour appears in spots and rarely appears on the face, unlike store-bought males, which have colour on their entire body.

3. Cannibalism of young seems to occur most often when guppies are in confined spaces. In nature, newborn guppies are often found in geographically distinct regions of a river from that of adults. Thus, wild-type guppies, unlike store-bought guppies rarely eat their own offspring. Reproduction in store-bought guppies is complicated by large elaborate tails in the males, thus mating is less common in pet guppies than in natural guppies.