The grouper, as seen in Babies and Hippos 2.

This grouper lives near the Hippo Punishment Whirlpool. Once, Whotsius and Lekis dropped Caeglinarol Inthaerion, then a young baby recruit, into the whirlpool. She dived down and found the grouper, who keeps small objects inside of him. He coughed up a hood and helped Caeglin get away from the hippo helicopter. It is possible we will see him again in the Hippo Story series.