Catfish

From Muppet Wiki

A "pop-eyed" Catfish is a member of the Riverbottom Nightmare Band in Emmet Otter's Jug-Band Christmas. He does backing vocals for the band and swims about in his tank supplying visual accompaniment not unlike a go-go dancer. He often backs up his cohorts' ill-tempered antics by spitting water in someone's face.