Cut fish into bite size pieces. Cover with pickling salt and 1 c. vinegar. Let stand for 5 days in fridge. Remove and wash until water is clear. Cover with cool water for 1 hour. then drain well. Slice the onions. (they are as good as the fish).
Make a brine of 2 c. whit vinegar, 2 c. sugar, 1 c. whit sherry wine and 1/4 box pickling spice. Heat the brine, but do not boil, then cool it.
Plae alternate layers of fish and onions into pints. Fill jars with brine and close. refridgerate. Ready to eat within 24 hours.