Ahh, Hattori Hanzo. I know that name very well. The fish could actually be named after a famous samurai named Hattori Hanzo;also known as Hattori Masanari. He was the head of the clan from the Iga region of Japan. Hanzō served Tokugawa Ieyasu loyally and well. He is commonly depicted as Ninja in manga and novel fiction. Hanzō was born a vassal of the Matsudaira (later Tokugawa) clan; he would later earn the nickname Oni-Hanzō (Devil Hanzo) because of the ferocity he displayed in battle.
Or
In video games these days and the arcade, the fish may be named after a fighting game character in a series called Samurai Spirits. He is also in different games as well.