Demersal - fish like flounder, catfish, stingrays, soles. Any fish that lives near the bottom of the water column. Pelagic - tuna, mullet, trout, redfish, sheepshead, drum. Any fish that swims around...
Pelagic fish are fish that live in the water column of coastal, ocean, and lake waters, but not on the bottom. Demersal fish live on or near the bottom.