Common Names: Guppy, Millions Fish

Scientific Name: Poecilia reticulata

Family: Poeciliidae

Subfmaily: Poeciliinae
Discovered: Known under its current scientific name since 1963, but was originally scientifically described in 1859 by W. Peters.

Geographical distribution: This fish is originally South America, including northern Brazil, Venezuela, Barbados and Trinidad. However, feral populations occur in many parts of the world. Some of these are from introductions to try control mosquito populations; unfortunately, they had little or no effect on the mosquitos, and sometimes a negative effect on native fish populations. Feral populations have been reported in Africa, Australia and Singapore.

Habitat: This fish occurs in a massive variety of habitats, from mountain streams to brackish river tributaries.

Sexing: Guppies can be sexed from about 4-5 weeks. The males have a modified anal fin, this is called the gonopodium.

Suitable Setup: Guppies are a very popular aquarium fish, and don’t require anything special. They are perfectly at home in a peaceful community aquarium. At least 2 females should be kept to each male, so they aren’t continually harassed. Also for the same reason, a tank housing both male and female guppies would ideally contain plants so the females can get out of the way of the mal. Although water chemistry is not critical for these fish, they prefer slightly acidic water. Salt is optional, only some, not all wild guppies live in brackish conditions.

Size: Males grow up to 3cm and females up to 5cm, although captive species may grow larger.

Temperature: The ideal temperature for this fish is 21 – 28°C.

Breeding: This fish is amongst the easiest to breed, in fact, it can be difficult to stop them! The females are nearly always pregnant, and can store sperm for up to 6 months. She will also give birth to between 10 and 40 fry every 4 to 6 weeks.
One of the best methods for getting plenty of healthy strong fry is to set up a breeding tank. A 10 Gallon tank is easily large enough, with plenty of plants for fry to hide in, such as Java Fern or Java Moss. Many people use breeding traps or nets in their community tanks. These are small plastic or net containers that float in the tank. These can easily stress adult fish, and lead to aborted pregnancies or even death. If you must use them, please only put the female in just before she is due to give birth, or even better, wait until the fry have been born and then catch and add them the trap. If you are using a plastic trap, then remember to change the water in it regularly.

Rearing of the fry: Guppy fry are easy to raise. At least a couple per brood would probably survive in a planted community tank. But if you want to save more of them, then you could use a separate “growing on” tank. A bare 10 gallon tank again would be enough. Just use an air powered sponge filter so the fry don’t get sucked in. You can feed them a variety of things such as liquifry for the first couple of days, then move up to fine crushed flake foods. Baby brine shrimp would also be a welcome addition. Remember to keep these tanks very clean as fry are more susceptible to pollutants than adult fish, so a small water change every day will be necessary, and also remove any faeces or dead fry.

Extra Notes: These fish are undoubtedly one of the most popular in the aquaria hobby. They come in a massive variety of spectacularly coloured strains. Many fish or pet stores recommend these fish as suitable for first time fish owners. They are easy to look after, but will usually struggle with a cycling tank, and would probably die, so they should not be added to a tank until the cycle has been completed.