The 'rays' in the picture you pasted in are apparently just photos under the ice, but some people thought they were animal corpses like the other 'exhibits'.
(I don't see freezing animal corpses in skating ice as any more objectionable than eating them.)
Link here:
https://www.theguardian.com/world/2016/nov/28/anger-as-japanese-skating-rink-freezes-thousands-of-fish-into-ice-as-gimmick
The 'rays' in the picture you pasted in are apparently just photos under the ice, but some people thought they were animal corpses like the other 'exhibits'.
(I don't see freezing animal corpses in skating ice as any more objectionable than eating them.)