Most pufferfish are extremely toxic and the stripebelly pufferfish is no exception. The stripebelly differs from other pufferfish in that its skin is unusually high in toxins, rather than being concentrated in internals organs.
These pufferfish will eat most anything and have a powerful beak (see the second photo) that can inflict a nasty bite. People have lost fingers and toes to these fish, so they aren’t to be messed with. That said, they mostly hang around just above the sea bottom and, as a result, I’ve never actually seen the striped belly that gives them their name.
In my attempts to identify what I see in the water, I use John P. Hoover’s book The Ultimate Guide to Hawaiian Reef Fishes, Sea Turtles, Dolphins, Whales, and Seals. His website is hawaiisfishes.com.