Emanuele Biggi / Great Fen / Raft spider (Dolomedes plantarius), adult female eating an invasive species of fish, Western mosquitofish, (Gambusia affinis), Alessandria, Italy, August.

Jean E. Roche / Mosquitofish (Gambusia affinis) female, introduced species to control mosquitos, Camargue, France, June. Biological pest control.

Alex Mustard / Female Mosquito fish (Gambusia affinis) swimming above weeds, below the surface of Lago Baratz, Sardinia, Italy. This species is originally from the Americas, but has been introduced into many countri...