I have a buddy that sells both. He’s saving me a gallon or two to make a fish based bait. Any tips on what to add like salt, benzoate, smoke oil or any other oil? I want a pasty very fresh fishy smelling bait.

Has anyone used shad or is it too watery?

If it is too watery grind it up and let it sit out for a bit in sun on a windy day. Or leave it the garage with a fan on it. I'd add salt to it like Marsyada recommended....layer of salt layer of fish layer of salt layer of fish in a bucket/container. Then stick in the freezer until ready to use. I did that with a 5 gallon bucket of bullheads and I'm still using them from a few years ago.

Ground, I've used sodium benzoate
Whole, I would use the salt

Not to get off task here...............Assume you are wanting this for coon/mink attractant. Both species of fish will "cause a pause" for a lot of furbearers so not an issue there. Preserving it as stated either of the sodiums (chloride or benzoate) will do fine. The better thought is on how you will apply it to the set comes next. Do you spoon or spatula it in a hole or pour it on a grass tuff? Maybe you dip it in a pvc pipe or maybe just scatter it on the beach/bank and use a little with dry cat food in a DP or in a BG box? From my side of the fence, an attractant of any type must be quick and easy to apply with simple tools. For years I used the old camera film bottles (black or gray) filled with ground fish at home and frozen ahead of time. I started the season with as many as 500 pre filled frozen containers. Arrived at my set spot, popped the top off, placed where I wanted and was gone. No big jar or spoon or to carry and the truck was not stunk up with a spilled bait container. Could put 1/2 dozen in my pocket or beside me in the truck to thaw if it was a cold day prior to placing. No muss - no fuss and no bait tools or big container to carry. My experience............................... the mike