The Colossal-Mouth Bass was a fish caught by Bender when the Planet Express crew went on a fishing trip in the Atlantic Ocean. Bender used the Unbreakable diamond tether and Amy's umbrella as a fishing rod and Hermes' Manwich as bait. It pulled the Planet Express ship under the water and led to the crew finding Atlanta.
Later, when Fry was rushing back to the ship to leave, he grabs hold of the diamond tether and the fish eats him, holding onto the tether. Bender claims this catch and it is a record. Bender was about to get $1,000 for catching it when Fry falls out of it, and the weight dropped to under the record. Hermes' Manwich also falls out. Zoidberg then opens the fish's gills from inside and tells everyone he is trying to sleep in there.