Pond Boss Forums STOCKING A NEW POND Types of fish to choose Will BC feed on Gambusia

Gambusia affinis is a small, harmless-looking fish native to the fresh waters of the eastern and southern United States. It has become a pest in many waterways around the world following initial introductions early last century as a biological control of mosquito. In general, it is considered to be no more effective than native predators of mosquitoes. The highly predatory mosquito fish eats the eggs of economically desirable fish and preys on and endangers rare indigenous fish and invertebrate species. Mosquito fish are difficult to eliminate once established, so the best way to reduce their effects is to control their further spread. One of the main avenues of spread is continued, intentional release by mosquito-control agencies. G. affinis is closely related to he eastern mosquitofish (G. holbrooki), which was formerly classed as a sub-species. Their appearance, behaviour and impacts are almost identical, and they can therefore be treated the same when it comes to management techniques. Records of G. affinis in Australia actually refer to G. holbrooki.

Predation of amphibian eggs and interference competition with tadpoles, resulting in injury or death to individuals. May have a negative influence on some frog species' choice of breeding habitat. G. holbrooki has been shown to predate upon the eggs and tadpoles of the critically endangered yellow-spotted tree frog (see Litoria castanea in IUCN Red List of Threatened Species), endangered green and gold frog (see Litoria raniformis in IUCN Red List of Threatened Species), and vulnerable golden bell frog (see Litoria aurea in IUCN Red List of Threatened Species) in Australia (NSW National Parks & Wildlife Service, 2004). Gambusia spp. have been implicated in the decline in the range and abundance of native fish species worldwide (Lloyd 1990) through predation and interference competition (McKay 1984; Howe 1995; Ivanstoff and Aarn 1999; Knight 1999). The species is purported to impact on macro-invertebrates such as rotifers, mayflies, beetles, dragonflies and molluscs (Anstis, 2002).

The introduction of exotic fishes to naturally fishless waters is often associated with declines in species native to those waters.
Mosquitofish, Gambusia affinis, have been introduced to waters worldwide for mosquito control. Taxa negatively affected by
mosquitofish potentially include fairy shrimp (Crustacea: Anostraca) that often show high rates of endemism, and which are
characteristic of naturally fishless wetlands on every continent. We tested the effects of mosquitofish on a fairy shrimp, Linderiella
occidentalis, in experimental ponds that included a community of native aquatic invertebrates. We supplemented field experiments
with lab trials to test whether mosquitofish preferred L. occidentalis to other prey. Survival of the fairy shrimp was significantly
reduced in ponds with mosquitofish. Only 16.9% of fairy shrimp survived in ponds with mosquitofish, while 64.0% survived in
control ponds. Fish presence also reduced abundance and biomass of other invertebrates. Results from feeding trials demonstrated
that mosquitofish frequently prefer L. occidentalis to alternative prey. Our results suggest that introduction of mosquitofish into
naturally fishless wetlands may lead to loss of diversity of their highly specialized aquatic fauna.