Orangeband Surgeonfish

That's a cool fish. It looks like there's a wrasse swimming alongside it.

When you see this fish on the reef, does it just look like a bright orange stripe randomly moving through the water?

No, the water is so clear here you see the whole fish. However, it's not common to see the fish with these background colours. Usually the fish is much darker, sometimes completely black, with just the orange showing. But you can always make out the outline of the fish. If the water was so cloudy or dark I couldn't see the fish, the orange would not be visible either.