Guppies, like most other livebearers, are members of the Poeciliidae family. Unique strains have been developed through selective and sophisticated breeding programs, and guppy genetics has become a science onto itself. The large numbers of tail colors, body colors, body patterns, tail patterns, and tail shapes results in an almost limitless number of combinations. The tails of guppies may be almost any color imaginable. Guppies are named by the color of the tail. So, if a guppy has a yellow body and red tail, it is called a red guppy.

The main upper body colors are gray and gold, but there are also metallic, albino, and other color variations.

The lower body pattern may be:

• Black - these are called "tux" or "half-blacks"
• Snakeskin - a rosette, chain-link pattern
• Cobra - rosette pattern with vertical bars

Tail patterns include:

• Solid - one color; clear varieties are often the most sought after
• Grass - pattern of small dots, resembling grass seed
• Mosaic - interconnected dots resulting in an irregular color pattern
• Leopard - larger spots

There are numerous tail shapes, which may be given different names in North America compared to Europe. Some of them are listed in the chart, below.

Guppies require a tank with at least 20 gallons of water, and are very tolerant of changing tank conditions. Plants should be hardy varieties such as Java Fern and Java Moss that can handle the increased water hardness in the tank. In order to reduce aggression among them, it is ideal to maintain several pairs together in the aquarium. Guppies should not be kept with Bettas or other fin-nipping fish, as they will harass them. Other peaceful fish would make good tank mates.

Males and females can usually be easily differentiated. The males are smaller in size, have brighter coloration, along with a larger tail fin, and pointed anal fin. The females are larger in size with a duller coloration, have a rounded anal fin, as well as a pregnancy patch on the lower portion of the body. When breeding guppies, ideally, the environment should have a covering of floating ferns and a breeding box to protect the fry. The fry are born fully developed, and can be raised easily in a separate aquarium or net breeder inside the tank. Adults may eat the fry if left to fend for themselves without the breeding box. The fry should be fed brine shrimp, micro food, and pulverized flakes.

Guppies are omnivores and require both algae-based foods as well as meaty foods. An algae-based flake food, along with freeze-dried bloodworms, tubifex, and brine shrimp will provide guppies with the proper nutrition.