I would imagine most lakes have been artificially stocked for angling. These vary from game fisheries with Brown and Rainbow Trout, to coarse fisheries with a mixture of usually Carp, Tench, Bream, Roach etc. Some coarse fisheries specialise in just Carp which can grow to up to 60lb. Over recent years there has been a growing trend to introduce species not naturally found in our lakes such as Catfish and Sturgeon. All fish transfers have to be licensed and supervised by the Environment Agency.