A Moment of Science

Mosquito Fish

Find out how these tiny fish can help do their part for hurricane relief.

two mosquito fish in the palm of a hand

Photo: eustatic (flickr)

A number of other fish eat mosquitoes as well, but mosquitofish are ideal for this operation because unlike those other fish, they can tolerate poor water quality.

Houses weren’t the only structures abandoned in New Orleans after Hurricane Katrina.

Swimming pools were also left vacant as residents left town. After the hurricane, the pools, much like the rest of town, were flooded with contaminated water. As the flooding retreated, the pools were left full of muck. The result, is lots and lots of mosquitoes, which, in turn, could mean encephalitis and West Nile virus.

However, there are guppy-like minnows known as mosquitofish that love to eat mosquitoes. In order to prevent a disastrous mosquito infestation, an entomologist has been breeding the native fish species in order to release them into the area’s over 6,000 abandoned pools.

The hope is that the fish will eat mosquito larvae before they’ve had the chance to mature and fly off in search of blood.

They can eat up to 100 mosquito larvae a day. A number of other fish eat mosquitoes as well, but mosquitofish are ideal for this operation because unlike those other fish, they can tolerate poor water quality. Because mosquitofish bear live young, their reproduction isn’t impeded by the water quality constraints of eggs. Mosquitofish produce anywhere from 50 to 100 young every six weeks, and as soon as they’re born, they’re gobbling up mosquito larvae.

Some have expressed concerns that the mosquitofish could take over other species. However, the fish already inhabit pretty much every body of water in Louisiana, and if their numbers do get out of control, they’ll take care of it themselves by eating their young. In fact, they’ve been used to control mosquitoes since as early as the 1930′s, just never on this scale.

  • http://www.facebook.com/phil.cusack.9 Phil Cusack

    It has been done on a larger scale in Australia in the early 20th Century. They killed off native species of fish which it was then found controlled the mosquito population better, So mosquito populations increased. They’re an invasive species that will also eat the babies of other fish ‘If their numbers get out of control’. Mosquito fish are now ILLEGAL to have in Australia due to the devastation they have on native fish, ILLEGAL to have as a pet or otherwise, Doesn’t that show something ? This has been done with hundreds of species hundreds of times before. There is always some native species that gets eradicated. Use repellent, don’t ruin the balance in the environment by introducing a pest-species of fish.

  • Susanne Winslow

    Try looking up Endler’s livebearers or those of the molly, goldfish, and carp family’s. You might find their real name, instead of Mosquito fish.

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