The USDA has some information on Canning Seafood and Fish
you might find informative, as does the University of Wisconsin - USDA Cooperative Extension's publication Canning Meat, Wild Game, Poultry and Fish Safely
While none of the information I could find comes right out and says that raw fish will be cooked when the canning is done ... I can't imagine it being anything else. Fish doesn't have to reach a very high internal temperature to be cooked (about 125-F) - and after 1.5 - 2.5 hours in a pressure canner in excess of 240-F, I don't think it could be considered as anything but cooked.
Canned fish, IMHO, is rather bland and is going to need something to gussy it up a bit - think what you normally do with canned tuna, mackerel, or salmon.
You can freeze your fish raw (for up to about 3-5 years) without having to worry about freezer burn if you use a vacuum sealer, such as one of the FoodSaver models.
Canning is just one
method of food preservation - and not always the best bet for everything.