Although they are ideal community tank residents with fishes of similar size and temperament, if you intend to breed guppies, it is best to house them in a species-only tank. You can house three pairs in a 10 US gallon tank or five to six pairs in a 20 US gallon tank. Available today in many color and fin varieties, all these guppies descended from the wild Poecilia reticulata.
Small, hardy, active, peaceful and pretty, the Platy is one of the most recommendable fish for any beginner. This little livebearer can be found in several different color varieties, developed through decades of selective breeding. As with many fish but especially livebearers, the Platy only has 2 things in mind: eating and breeding. It'll swim around the entire tank and eat just about anything, including algae, which makes it a handy cleaner fish as well.
The Montezuma swordtail is one of the true wild swordtails originally introduced into the hobby. Today almost all of the swordtails available at local fish stores are many generations removed from wild fish such as this and have many different colors. The wild Montezuma most resembles what is sold today as the green swordtail. However, the wild fish is larger, and in addition to the green body color it has a number of black spots — most evident on the male.
Fish breeders have developed many forms of long-fin swordtails. By making use of the fact that these fish are prolific and produce mutations quite often, expert aquarists have managed to selectively breed for the longer fins. The first ones were called the Simpson hifin swordtail. There have been many others since these were introduced many years ago. Aquaculturists continually develop new strains of long-fin swordtails.
Mollies are some of the easiest species to raise once you know what you are doing. They can be raised equally in fresh water, brackish, or fully saltwater. The key to keeping mollies is that the tank needs to get an adequate amount of sunlight, so that natural algae can grow in the tank, which they will quickly devour like crazy. Also, they need an abundance of live plants if possible.
The Sailfin Molly is perhaps the most beautiful of mollies. It is a small sized fish, with males reaching about 4-5 inches in length and females reaching closer to 5-6 inches in length. Captive bred fish come in a variety of colors, including green, black, orange, and white. The male's dorsal fin is larger than the female. The Sailfin Molly is fairly easy to keep in a community tank that doesn't include more aggressive fish. An ideal environment would include several females to a single male, as males tend to be aggressive toward each other.