Pelagic fish are those fish that live in the open ocean, often in the middle of the water column. They are usually found in large schools, and are a crucial part of many marine ecosystems. Some common synonyms for pelagic fish include open ocean fish, oceanic fish, offshore fish, and deep sea fish. These fish can be found in a variety of sizes and shapes, ranging from tiny fish like sardines and anchovies, to larger species like tuna and billfish. Regardless of the specific species, pelagic fish are an important source of food for many other marine animals, including sharks, whales, and seabirds.