The Master of the Swamp (沼の主, Numa no Nushi) also known as the Lord of the Lake, is a whale-sized fish living in the swamp of Whale Island.
It is a giant fish several times larger than Gon. It has the overall body of a scaly fish with sharp teeth and oddly enough it has the thin skeletal legs of an arthropod, with 16 legs on the left and right side of its belly (4 on each side in the 2011 anime). In the manga, it is primarily red and pink in color. In the 1999 anime it has a dark red body with a white underbelly and yellow fins. In the 2011 anime, it is a blue fish with a light green face and underbelly, and dark blue fins.
Hunter Exam Arc
Despite its difficulty of capture, five fishermen being unable to reel him in at once, Gon caught the fish at the age of eleven. In the 2011 anime adaptation, Ging is said to have achieved the same feat when he was twelve.
In the Nippon Animation adaptation, Gon releases the fish after Mito signs his Hunter Exam application card. However, its fate is unknown in the manga.