Most butterflyfish have some sort of eye camouflage, so the bluestripe butterflyfish is unusual in having none. The diagonal blue stripes also make it stand out from the crowd. And where most butterflyfish have relatives in the Pacific, the nearest relative of the endemic bluestripe butteflyfish, is the east coast of Africa
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.