How long is seafood good if not refrigerated?

There actually isn't any specific time frame. It all depends on the type of seafood, the conditions under which it has been stored before and after sale and the size of the bacterial load.

If you are referring to refrigerated fresh fin fish, use it within 1-2 days of purchase.

See this site from Clemson University Cooperative Extension Service:

http://hgic.clemson.edu/factsheets/HGIC3522.htm