Pelagic fish are species which live and feed away from the bottom of the sea or lakes. This are of water is called the Pelagic Zone and is away from the bottom of the sea or lake and also away from the shore. Pelagic fish tend to contain more fish oil than demersal fish. Pelagic fish can contain up to 30% fish oil. Examples of pelagic fish include Herrings and Bluefin Tuna fish.