Red Lionfish (Pterois volitans, german: Pazifischer Rotfeuerfisch, french: Poisson-scorpion). It has venomous spines. (910k)
Here are the pictures of Red Lionfish (Pterois volitans) with links to the pages on which they appear, links to the full sized picture, and the description of the picture with links to the entry in iNaturalist (inaturalist.org)
All pictures are © Dr. Günther Eichhorn, unless otherwise noted.
Mauritius Nature
Dr. Günther Eichhorn Travel Website
Soaring website