A Creep in the Deep (S02E20)

When the Rangers investigate a series of bizarre attacks on seafood restaurants and trucks, they learn that Captain Finn, an anchovy bent on revenge, has taken over command of Captain Nemo's famous submarine, the Nautilus. His crew of squid, octopi, and other sea creatures is trying to liberate the sea community from the slavery of the landwalkers. Finn tries to release Nemo, a killer whale, from Sealand, but is foiled by the Rescue Rangers. Furious, the anchovy decides to give the landwalkers a fish-eye view of life by ramming the County Dam to put the entire city under water! (iTunes)