Blue Hippo Tang (Paracanthurus hepatus)

Paracanthurus hepatus is the fish that launched a thousand aquariums after Finding Nemo, but the real animal is more interesting than the cartoon — that royal blue body hides a retractable scalpel at the tail base, and startled individuals have been known to leap clean out of open-top tanks. Juveniles wear the same electric blue with cleaner black markings that fragment and shift as the fish grows into its adult pattern.

Care level: Moderate · Temperament: Semi-aggressive · Max size: ~12" · Min tank: 125+ gal · Diet: Herbivore, algae + herbivore pellets