Michigan State University Extension
Preserving Food Safely - 01600572
Although freezing is the easiest way to preserve fish, canning does offer some advantages. Canned fish is shelf stable and will not take up freezer space. Canning produces a moist, flaky product. Canning also eliminates the bone problem because bones soften and become edible. Mullet (suckers) and other bony fish are often canned in the Great Lakes area for this reason.
Use only half-pint or pint jars for canning fish; do not use quart jars. Jars must be thoroughly clean. However, it is not necessary to sterilize them. Just wash them in hot, soapy water; rinse well.
Close jars with two-piece canning lids. Wipe jar rim clean. Put lid on, with sealing compound next to glass. Screw band down firmly, so that it is hand tight. Some lids with sealing compound require boiling or holding in boiling water for a few minutes before use. Follow the manufacturer's directions.
The only safe way to process fish is in a pressure canner. To prevent any risk of botulism food poisoning, the pressure canner must be in perfect order and canning directions must be followed exactly. Unless you are absolutely sure of your pressure gauge and canning methods, boil home-canned fish for 15 minutes in a covered pan before tasting or using. Boiling will destroy botulism toxin.
Fish that has been frozen may be safely canned. Thaw fish in the refrigerator and process as soon as it has thawed. Processing the fish promptly after thawing is essential for a safe product.