With its terrifying grey-green color, black Marlin is a creature of nightmares and one that should be respected. It is the one that looks like a black top half with fins on its bottom half that lives at depths of hundreds of meters in the deep ocean. Though, there are no fishes that match the black Marlin, it has one special place where it is the king. This fish inhabits South Atlantic Ocean, and in tropical waters of Asia. They are actually non-aggressive fishes that are not afraid of humans and can be kept as pets.