mixing salt

I've seen a few posts where people have mentioned adding mixing salt to the water. How much mixing salt should I put in a your average size minnow bucket?

Thank you!

I've never put salt on crappie minnows. We use salt in our herring tanks though.

Don'y know but they use alot at fish farms when they first bring fish into tanks to toughen them up.

it just seems like it would kill them if you put to much, it seems like it wouldnt help their gills to much