Related to https://bugs.mojang.com/browse/MC-61506 "Rabbits notice / follow spectating players" a pufferfish will inflate as approached by a spectator and deflate as the spectator leaves the area. I note that the pufferfish doesn't "move" as it will when the player is in creative or survival, it seems frozen in place. But inflating/ deflating still triggers. The puffer fish does NOT rotate or follow/ flee a spectator.

This appears like the "bunny" bug, though I note spawned rabbits correctly DO NOT notice players, just the puffer fish.