What kind of fish is this white blue-stained fish?
I don't know whether this helps, but that looks like a parrot fish.  I had a look online and also didn't find anything with that distinctive pattern. The closest I could find was Scarus ghobban (common names include blue-barred and blue-trim parrotfish), which is highly variable but the blue edges on the fins seem constant.

According to the sources linked above this fish can be seen in areas with sandy bottoms, so that seems consistent with your photograph.

Reference pictures: