With great luck, this Gemmy-related page is described on Wikipedia.
Big Mouth Billy Bass is an animatronic singing fish, popular in the early 2000s. Designed by Gemmy Industries, it turns its head towards the user, and wiggles as it sings kitschy cover songs, such as "Take Me To the River" by Al Green and "Don't Worry, Be Happy" by Bobby McFerrin. The fish is rubber, stretched on a trophy-like plaque, what at first it appears to be a mounted game fish. The concept was adapted into a Christmas version, fish bones, and a standing fish with a microphone. The concept was also adapted into a large and medium deer head, and a medium bear head.