Jake the Dog as Marlin
Finn the Human as Nemo
Daphne as Dory
Benson as Gill
Grizz as Bloat
Raven as Peach
Rigby (and Mordecai) as Gurgle
Gumball (and Darwin) as Bubbles
Pearl and Amethyst as Deb/Flo
Pizza Steve as Jacques
Daffy Duck as Nigel
Gumball's Classmates as the School of Moonfish
Greg Universe as Crush
Steven Universe as Squirt
Uncle Grandpa as Mr. Ray
Ice King as Bruce
Nathan and Dustin as Anchor and Chum
Squeaks as Blenny the Worried Fish
Snowballs the Ice Monster as the Anglerfish
Birds (Clarence: Goose Chase) as the Seagulls
Tina Rex as the Whale
Bugs Bunny as Jerald the Pelican
Clarence as Tad
Amy Gillis as Pearl
Jeff as Sheldon
Robin as Dr. Phillip Sherman
Starfire as Barbara
Tinia as Darla Sherman
Lady Rainicorn as Coral
Thes as the Barracuda
Chad,
Fred,
and EJ Randell as the Fish Parents