Stickleback Mutant (11, 36, 50-51) - A stickleback monster. It can shoot the spikes from the top of its head and throw razor scales. Stickleback Mutant was first seen when the Gorugomes Fruits were becoming scarce. Stickleback Mutant was later seen when the Gorgom High Priests became Grand Mutants. Stickleback Mutant later catches three Gorgom Mutants trying to flee from the headquarters and kills them. Stickleback Mutant was ordered by Shadow Moon with the task of eliminating Whale Mutant. Stickleback Mutant ambushes Kotaro and Whale Mutant and drags Whale Mutant underwater. Stickleback Mutant starts to overwhelm Whale Mutant. Kotaro catches up to them and transforms into Kamen Rider BLACK. The Creation King intervenes and pulls Kamen Rider BLACK to his palace where Shadow Moon is waiting. Stickleback Mutant succeeds in its mission. Stickleback Mutant alongside the Handmaiden Mutants watched the fight between Kamen Rider BLACK and Shadow Moon. After Shadow Moon was taken down, Stickleback Mutant stepped in to fight Kamen Rider BLACK. Kamen Rider BLACK easily avenged Whale Mutant by killing Stickleback Mutant with the Rider Kick.