Guppies
Poecilicdae
INDEX
WHAT ARE GUPPIES?
THE PERFECT BIOLOGICAL CONTROL OR A NUISANCE INVADER?
MANAGING PEST CONTROL
MOSQUITO EATING FISH IN THE BAHAMAS
WHAT ARE GUPPIES?
A Guppy (Poecilia reticulata) is a small member of the Poecilicdae family, which also includes mollies, platies, mosquitofish and swordtails. This is a family of freshwater fish and contains about 293 different species. The family are livebearing or ovo-viviparous. This means that the females retain the fertilized eggs inside of them and the fry (young fish) hatch inside the mother, coming out of the mother as live young. This is a highly evolved form of reproduction that enables the parent to increase the survival rate of their young.
The females tend to be a drab brown to grey color and are about 3cm in length. In contrast, the males are smaller, about 2cm long and have a colorful tail fin. The male fin color varies depending on where they are from. People have created extravagant color variations in guppies by selectively breeding them.
Guppies are very easy to keep in a tank and this is why they are so popular as pets. They were first discovered in Trinidad in 1866 where they are often called “millions”, referring to their ability to populate. They originate from South America namely; Venezuela, Barbados, Trinidad, northern Brazil and the Guyanas. They tend to be surface feeding, voracious predators and though they are known for eating mosquito larvae they also consume other small insects, zooplankton and detritus (dead or decaying organic matter – often plant material).
Return to Index.
THE PERFECT BIOLOGICAL CONTROL OR A NUISANCE INVADER?
Though Guppies originate from South America, today they are found in every inland water body throughout the world, to aid in mosquito control. There are many species within this family of fish that have been introduced around the world as mosquito larvae predators but one species in particular that could be considered the official mosquito fish is the Western mosquitofish, Gambusia affinis. This species are now found all over the world due to its reputation for eating mosquitoes. According to US Navy research statistics, a large female Western mosquito fish is able to consume 225 mosquito larvae in an hour.
Despite these findings, these fish are being blamed for harming aquatic ecosystems because of their highly predaceous habits. Arguments state that when these fish are given only mosquito larvae to eat they do tend to eat a lot of it but in the wild these fish show much more variation and eat a wide variety of small organisms, altering the zooplanktonic, insect and crustacean communities. These fish have also been blamed for attacking and even killing many small native fish, out competing and eventually replacing the native and often more efficient mosquito eating organisms.
Return to Index.
MANAGING PEST CONTROL
It is unanimously accepted that mosquitoes are a nuisance and a disease threat. How to control their populations, however, is not so unanimous. Pesticides have long been the standard approach to the problem but this is costly, dangerous to the health of other organisms (including humans) and is only a short-term solution to the problem.
Pest control needs to be done using a variety of methods in a manner that controls the pest populations instead of eradicating them. This approach is known as Integrated Pest Management (IPM). In this approach, pesticides should be considered as a last resort rather than routine.
Biological control (control using other organisms) is becoming a very important, cost effective, long term tactic when dealing with pests. However, like with the example of the mosquito fish, a lot of research needs to be done before a foreign organism can be brought into a new country to help reduce pests. And, in this case, all scientists do agree that the problems caused by the toxicity of pesticides are worse than the problems caused by the mosquitofish. But as with Gambusia and the Guppies, these fish have been introduced to countries that already had an effective mosquito eating fish present and their introduction has replaced those fish due to their aggressive behavior. This is why so many feel so strongly against the introduction of Gambusia and Guppies around the world.
Return to Index.
MOSQUITO EATING FISH IN THE BAHAMAS
The Bahamas has a couple of native species of Gambusia, some of which are unique to the Bahamas. The Caribbean Gambusia (Gambusia puncticulata) is found throughout Cuba, Jamaica, Cayman Islands and the Bahamas. The Bahamas also has a species which is endemic (only found) in the Bahamas, Gambusia hubbsi, which is found only on the island of Andros. Another species which is endemic to the Bahamas is known as the Bahamian mosquitofish, Gambusia manni.
Today many species of the Poecilicdae family are found in the canals and ponds of the Bahamas. On the island of New Providence you will often encounter mollies, platies and swordtails and especially the Guppies (Poecilia reticulata). The Guppies were introduced to nearly all the islands of the Bahamas as a method of mosquito control by the Department for Environmental Health.
No studies have been conducted on whether these introductions have had a negative impact to the ecology of the ponds in the Bahamas.
Return to Index.
|
