Mosquitofish:
- Life History:
- Gambusia, also known as mosquitofish, belong to the Poeciliidae family (live bearers), which includes other
fish such as guppies and topminnows. Mosquitofish prefer quiet, shallow ponds, lakes, ditches, drains, marshes and
sluggish creeks with clear water and aquatic vegetation. They are most at home in warm water temperatures;
tolerating water temperatures between 40 and 100 degrees Fahrenheit. Their life span is short, probably less than
15 months. They are ovoviviparous (live bearers).
- Gambusia reach maturity in 4 to 10 weeks. Each female can produce three to four broods in her lifetime, and
each brood can vary from 40 to 100 young. The young are born in spring and summer when they are about 0.4 inches
long. Adult length ranges from 0.8 to 2.5 inches. Mosquitofish feed at the water’s surface and eat a variety of
macro-invertebrates; including mosquito larvae, other small insect larvae, zooplankton and aquatic plants such as
algae and diatoms. Gambusia are aggressive and may also feed on fish fry.
- Gambusia have been used for mosquito control in the US since the early 1900’s. Various agencies throughout the
world have developed stocking guidelines for mosquito control in swimming pools (abandoned), ornamental pools,
ditches, wetlands, mine pits, storm water and waste water disposal lagoons, natural creeks, animal watering
troughs and small seasonal or permanent ponds. Recommended stocking rates in the US range from 15-100 fish for
back yard ornamental ponds to 2,500 fish/acre for small ponds and ditches. Reports from mosquito control
organizations indicate that the greatest problem associated with the inability of Gambusia to control mosquito
larvae are aquatic vegetation, inadequate fish numbers or a lack of distribution by the fish in a water site.
- There is no garauntee that mosquitofish will provide 100% control, but in certain situations, it is believed
that they can help reduce mosquito populations.
- Distribution:
- The natural range of the mosquitofish was New Jersey south to Florida and the Gulf of Mexico, and in the central
US from southern Illinois to Alabama. Gambusia affinis, the western mosquito fish is no longer considered the same
species as the eastern mosquitofish, Gambusia holbrooki. G. affinis and G. Holbrooki have been introduced
indiscriminately throughout the world in temperate and tropical climates for mosquito control wherever mosquito-born
diseases pose a threat to human health. For example, mosquitofish have been introduced into southern European
countries, Germany, Thailand, Africa, Russia and Argentina. Gambusia have been introduced or are native to at
least 43 states in the US.
- In Washington, Gambusia are not widely distributed. Gambusia are known to be present in Benton and Clark counties.
Gambusia have been located in other areas as well, but as for all the sites of this fish, it is still unknown.
- Impact of Introduction:
- Mosquitofish can compete with other animals for available resources and Gambusia have been blamed for predation of
the fry of some fish. Importation and transportation of Gambusia in Washington State requires approval and a permit by
the Washington State Department of Fish and Wildlife (WDFW). Benton County MCD has a permit to transport Gambusia
affinis. But only certain sites meet the requirements for introduction. Introduction is determined on a case-by-case
basis to insure that the mosquitofish are placed into an isolated site (no connection to lakes, rivers, streams or
canals) where they may have a positive impact upon the existing or potential mosquito populations.
- What to do if you want Mosquitofish:
- Some examples of sites that have shown to benefit from mosquitofish are decorative ponds, water troughs and small
isolated ponds.
- We work in conjunction with the Washington Department of Fish & Wildlife for planting Gambusia, so there is a form
that must be reviewed and signed before we can deliver the fish and we will have a few questions pertaining to the water
site. If you feel that you have a water site that may benefit from the addition of Gambusia, you have some options
available. Please keep in mind that the site needs to be isolated without any connection to rivers, streams, lakes or
the canal system.
- You can give us a call at (509) 967-2414 and make a request to receive Gambusia, you can
download the form from our website or fill out our
online form. If you call us we will mail, fax or email the necessary form and after
we receive the completed form back, we will put you on a list for delivery.
