Members of the N.J.M.C.A. Research and Development Committee have been researching the effectiveness of Gambusia in various mosquito breeding habitats for the past three years. Gambusia populations in N.J. have been manipulated since 1905 for mosquito control purposes. With the environmental awareness that now exists, Gambusia have become an important mosquito control alternative to pesticides.

Gambusia use in an area is dependent upon sufficient water levels existing for the fish to survive and access any larval mosquitoes present. Although an eventual drydown may eliminate the fish from an area, the area should be considered for stocking if a few months larval control can be achieved.

Gambusia are more effective in some situations than others. They generally work quite well in unused swimming pools, abandoned sewage lagoons, mine pits and permanently flooded stormwater facilities. Other larval habitats do not consistently provide a suitable site for Gambusia stocking but at times exhibit the proper characteristics that enable stocking to occur. These sites include freshwater swamps, ditches and woodland pools.

The most important observation that was consistent throughout the study was that drydown was the primary cause of fish loss in an area. Low fish density was the reason many larval mosquito populations were insufficiently controlled by GambusiaAnopheles spp. mosquitoes are particularly hard for mosquitofish to control when emergent vegetation provides them harborage.

Throughout all Gambusia stocking situations the area should first be a documented mosquito producer. The area should also be contained so that the fish cannot escape. The area should be monitored to follow the progress of the fish. All Gambusia stocking in N.J. should be coordinated with the Office of Mosquito Control Coordination using guidelines developed by the N.J. D.E.P.

Gambusia Stocking Rates

Bird bath (large): 10 fish/site

Ornamental pond/swimming pool: 35-100 fish/site (depending on size)

Stormwater facility: 1,000 fish/acre

Ditches (1-2 yds wide): 1 fish/every yard of ditch length

Mine pits: 2,500 fish/acre (immediate control)

Freshwater swamps, Woodland pools, Sedimentation ponds: 1,000 fish/acre (inoculation rate; control not needed for 2 or more months)


Center for Vector Biology