It is in the family of bony fishes. They can grow up to 4 inches long. They are found world-wide, 600-4500 feet deep. They are mostly found in the Pacific western. The luminesent lights point down from the body, and the eyes point up from the body. They are light weighing, their avg. weight is 1/38 of an ounce! The hatchet fish eats cope cods and the fry of other fishes. The tuna eats the hatchetfish if it swims to close to the surface of the ocean.