The Iowa Department of Natural Resources is planning to introduce a predatory fish to help reduce the population of bottom-feeding fish in the lake. D-N-R fisheries biologist Jim Wahl says reducing the amount of carp and bullhead in the lake will help since those fish feed on the lake bottom, stirring up sediment.When they stir up the bottom, that exposes nutrients that make algae grow, hurting the lake’s water quality. Wahl says the D-N-R recently completed a study to estimate the number of bottom-feeders in the lake. Carp and bullheads make up about half of the lake’s fish population. Wahl says they are planning to introduce about 10-thousand flathead catfish into the lake. The fish are being raised as the state hatchery near Centerville and they hope to release the eight-inch fish next summer. Wahl says the introduction of flatheads into the lake will not make for an instant solution or change in the lake.The stocking of flatheads has worked on smaller lakes in Iowa, Wisconsin and Minnesota — but he says Clear Lake is much larger and will take much longer. The D-N-R last year stockpiled about one thousand flatheads in the lake.