These are not fish; I mean that in the way that Magritte meant "Ceci n'est pas une pipe." Yes, these are images of fish, but if we are discussing medium they are paint and resin and they leave me in awe. Riusuke Fukahori layers resin and paint until a 3D image appears to be an actual fish in a wooden container. The best explanation can be seen in this video:
If you are proficient in Japanese, Riusuke Fukahori's website can be found here.