Boxy fish about 4 or 5" long with a network of 5- and 6-sided darker markings on the back and sides of a white-tan body.
Warm coral reef around Hawaii.
The Waikiki Aquarium has a number of local fish in its tanks which are so much easier to photograph than those seen while under water snorkeling! This odd-looking tropical fish is related to pufferfish, and its defense mechanism is to inject a toxin into is mucosa and shed it into the water which quickly dissolves it. Nearby animals are all affected by the toxin which is surprisingly closely related to certain detergents.