Black Marlin are found in tropical and temperate waters of the Pacific and Indian Oceans. They are an offshore species that is known for being one of the strongest fighting fish of the ocean. They are meaner and more aggressive than a blue marlin of the same size. Because of their aggressiveness and willingness to put up a fight, it is not uncommon to hear of a black marlin dying as a result of being caught. Black marlin appear almost identical to blue marlin in body structure. The color of their back is where they differ from a blue marlin. The black marlin has a back that is much darker. It is actually a very dark blue, but because it is so dark, it has been given the name black marlin.