For quart jars:

2 tbsp. catsup
2 tbsp. vinegar
2 tbsp. salad oil
1 tsp. salt

Put in bottom of jar before fish. Soak 24 hours in 1/2 cup salt to 1 gallon water. Rinse well, drain and pack in cans. For pint cans - use 1/2 of amount called for. Process 90 minutes at 10 pounds pressure.