Pelagic
Living in open water away from the bottom, as tuna, sardines, mackerel and flying fish do.
Also: open water, epipelagic
Pelagic fish live in the water column, not on the bottom. Small pelagics such as sardines, anchovies, herring and the Indian oil sardine form huge schools near the coast and are caught by purse seines and ring seines. Large pelagics such as tuna, swordfish, marlin, mahi-mahi and oceanic sharks roam whole oceans. The sunlit top 200 metres is called the epipelagic zone. Pelagic fish tend to be streamlined and countershaded, and many never stop swimming.