For bait or consumption?
If you want to use it for bait, I personally found, back when I lived in Ontario, oh natural is most effective. If you decide to cure, you must cure before you store either by freezer or fridge. But here's some methods a few of my buddies back in Ontario uses.
Method 1
brown sugar
Method 2
store bought powder or liquid cure
Method 3
borax and if you want to add some colour, sugar free jello
Method 4
1/2 c salt and 1/2c sugar
Method 5
sodium sulfite
Method 6
Equal parts sugar, salt and borax
Method 7
air dried. air dry on wax paper in the fridge until they are shrivelled up and rock hard. When your ready to use, tie up in roe bag and rinse throughly in water the day before so that the eggs reconstitutes.