The carefully planned introductions of European perch (Perca fluviatilis), have taken place at five sites in the county: Sandy Water Park; Morolwg, Ashpits and Lower Lliedi reservoir in Llanelli, and a private pond in Cynheidre.

Their introduction follows extensive research into predator-prey relationships. Perch, a native species, have been identified as a natural predator of Topmouth gudgeon and provide an effective method of population control without the need for chemical intervention. Topmouth gudgeon is listed under the retained EU Invasive Alien Species Regulation 2014 and is a GB rapid response priority species.

Its presence threatens native wildlife and habitats, and its rapid spread could have serious national ecological consequences.