The Goldfish

One of them was referred to specifically as a goldfish in episode 319. Appearances
episode 312 -- "Octopus' Garden," at least twelve goldfish
episode 319 -- Muppet Sports, one with Contender 980116
episode 402 -- "Want Some Seafood Mama," three on backup
episode 417 -- "Three Little Fishes," three with their mother (Louise Gold)
episode 514 -- "Baby Don't Get Hooked on Me," eight
episode 519 -- "F  ...