Yes, @MargotRobbie is correct (sorry, I haven’t figured out yet how to link usernames). Hot smoked food usually doesn’t keep for more than a few days, if that, because it is cooked. AFAIK, in cold smoking, the smoke itself even has a preserving effect because it kills surface bacteria and dehydrates the outer crust, but the fish is also salted or brined. As noted in other comments, there are a wide variety of different techniques. Note: I’m not an expert, so I may be off on the details. I just used to work next door to a smokery and chatted with the owners sometimes.