Clearfin Lionfish [Pterois radiata]

The Clearfin Lionfish, Tailbar Lionfish, Radiata Lionfish or Radial Firefish, Pterois radiata, is a carnivorous ray-finned fish with venomous spines that lives in the Indian and western Pacific oceans.
It is the only lionfish species with blank spines. But it can also be recognized by the pair of horizontal white stripes on its tail. (text source: Wikipedia)

Picture: The blue hole, Dahab, Egypt by Sami Salmenkivi