From Muppet Wiki

Fish characters include:

• Cosmic Fish, on Muppets From Space
• The Fish Singer, on The Muppet Show
• The Gills Brothers
• Goldfish
• Moby
• Norval the Fish
• Pop-eyed Catfish, in Emmet Otter's Jugband Christmas
• Shark (Muppet Show)
• Shark (Sesame Street)
• Smokey the Salmon
• Tillie
• Walleye Pike
• Wanda Cousteau, on Sesame Street