You can search for pickled herring recipes. They should work equally as well for what you want. You may want to search several and compare to get exactly what you think might work best for you. Here's one I picked at random from a pickeling site.
Ingredients:
3 mild herrings
1 large spanish onion sliced
1 tsp. mixed pickling spices
1 lemon sliced or 2 1/2 tbsp. lemon juice
2 bay leaves
10 peppercorns or scant 1 tsp. cracked pepper
1 cup water
1/4 cup vinegar and
1 tablespoon brown sugar
Directions:
Wash herrings, removing head, tail and fins. Soak in cold water to cover for several hours. Combine spices, lemon, bay leaves, peppercorns with water, vinegar and brown sugar. Bring to boil, set aside to cool. Slice fish into 1 inch slices. Place in sterilized pickling jar. Add sliced onions and cooled liquid to jar and cover. Shake to mix contents. Set in refrigerator for 2-3 days. Check occasionally to shake and push down onions. Bring up bottom pieces of fish to get top pieces down into liquid.
