this guy is so far 75/50 after 4 hands, but he is playing one reg table and is not full stack. So I would assume that he is a fish.

calling is probably out of the question, because of the left spr - less than one. So its either fold or shove. Against a reg at this limit, I would fold and call against a normal 4bet size. At higher stakes I would probably shove..
But now, not sure how to approach an unknown fish.. I usually give them some credit unless they do something really silly.
So I would say in order to avoid attracting the variance, we can just let this go and probably shoving JJ+ and AK.. but I am still concerned that sometimes they are just clicking buttons with hands that looks fine ATs,AJs, 88+,AQo,KQs.. you got the point...