Headshot of a silver unicornfish (Naso), photographed at uShaka Marine World in Durban. Several species of unicornfish headshot have a hornlike extension of the snout which begins grown when a young fish reaches about 13 cm (5″) in length. They are generally not aggressive to each other, but when they do fight they use sharp scalpels by their tails as weapons, not their horns. Photo by Alan Sutton.