In a series of laboratory experiments, I examined the attraction of bluegillsLepomis macrochirusto cover as a function of light intensity and orientation of underwater structures. Changing the density from one fish to five fish per aquarium did not change the results. Fish always preferred the lowest light intensity available. In very low light, they chose areas with structure more frequently than open water. Their choice of horizontally or vertically oriented structure was influenced by the size of the interstitial spacing between the structural components. Horizontally oriented structures were used less when the interstices were smaller than the body depth of the fish, and they were used less than vertically oriented structures. When artificial habitats are added to water bodies, the orientation and the interstitial spacing of the structure may influence the size of fish attracted.