the swim bladder to the pharynx is closed so air is unable to pass through from the mouth, these fish are called physoclists. Specifically in perch, the gas bladder can vary from 12% to 25% of oxygen and 1.4% to 2.9% of carbon dioxide gas. Perch reproductive organs include either a pair of testes (sperm-producing) or a pair of ovaries (egg-producing). Habitats Perch are classified as carnivores, choosing waters where smaller fish, shellfish, and insect larvae are abundant. The perch can be found in the central parts of the United States in freshwater ponds, lakes, streams, or rivers. These fish can be found in freshwater all over the world, and are known to inhabit the Great Lake region, in particular Lake Erie. These fish inhabit bodies of water where vegetation and debris is readily accessible. In the spring when the perch chooses to spawn, they use vegetation to conceal their eggs from predators. Fishing Perch are a popular sport fish species. They are known to put up a fight, and to be good for eating. They can be caught with a variety of methods, including float fishing, lure fishing, and legering. Fly fishing for perch using patterns that imitate small fry or invertebrates can be successful. The record weight for this fish in Britain is , the Netherlands , and in America . Perch grow to around and or more, but the most common size caught are around and or less and anything over and is considered a prize catch. See also For other perch not in the genus Perca, see Perch (disambiguation). References External links Sport fish Vermont cuisine Taxa named by Carl Linnaeus