Alex Mustard / Bluestreak cleaner wrasse (Labroides dimidiatus) sticking its head into the mouth of a Red Sea fusilier (Caesio lunaris) during a cleaning session. Small Crack, Sha'ab Mahmud, Sinai, Egypt. Red Se...

Juergen Freund / A blue wall of Lunar fusiliers (Caesio lunaris) and Bluestreak fusiliers (Pterocaesio tile) blending in with the blue of the water. Misool, Raja Ampat, West Papua, Indonesia