Shrudlu

Captured early in the story, Aquaman tried to talk his way out of the aquarium by demonstrating there were stranger and more interesting sea creatures than him on Earth.  A swordfish with two swords, an octopus with elastic tentacles, a flying whale, a Bahamian Scallop and a Giant Bat Fish (!) all failed to impress them.  They had seen similar creatures in other worlds. 
 
Aquaman finally convinced them to let him free and replace him with a rare “tank fish, an armored fish with electrified feelers, multiple tentacles, and a sword” . Actually the fish was only electric eels, octopi, and a swordfish, convinced by Aquaman to act together. The armor was an empty shell. Shrudlu was fooled in taking with him the shell while leaving behind the creatures who had helped Aquaman.