SD Least Wanted.comAquatic invasive Species

SD Least
View Larger Image © David Ostendorf

Western mosquitofish


Gulf Coast States and Southern Mississippi River


W. Mosquitofish are typically dull grey or brown. They have a flattened head with an upward pointing mouth, and a rounded tail.


These fish are extremely aggressive and can cause drastic reductions in small native fish populations. Some studies show they may benefit mosquito populations.

Range Expansion:

W. mosquitofish were initially introduced in many areas to control mosquito populations. It was believed that they would consume more mosquito larvae than native species; however it was found that they are less effective at mosquito control than native fishes.

South Dakota Distribution:

Keep Aquatic Invasive Species Out of South Dakota's Waters


  • Remove aquatic plants and animals before leaving any waterbody.
  • Drain water from bait bucket, live well, bilge and motor before leaving any waterbody.
  • Dispose of unwanted bait, fish parts, and worms in the trash.
  • Spray/wash boat, trailer, and equipment with high pressure hot water on your way home or at home -OR- dry everything for at least 5 days.
  • Always report questionable species.


  • Never release live animals or plants - this includes all aquarium species, bait, pets or water garden plants. Do not release these into the wild. If you cannot find another home for animals, dispose of them in a trash can or bury them. Seal plants in plastic bags and dispose.


Because these hitchhikers can:

  • Reduce game fish populations
  • Ruin boat engines and jam steering equipment
  • Make lakes/rivers unusable by boaters and swimmers
  • Dramatically increase the operating costs of drinking water plants, power plants, dam maintenance, and industrial processes
  • Reduce native species
  • Degrade ecosystems
  • Affect human health
  • Reduce property values
  • Affect local economies of water-dependent communities.
More information on