I have used Francodex Oatmeal Shampoo for several years with great results.
Just remember that ferrets don't need to be bathed frequently.  I went
from once a month to only as needed.  Inola gets one bath a year at most.
She has a yummy natural chocolate smell, anyway.  Liu gets bathed more
frequently since he loves baths and get tail acne.  It's better to keep
their bedding clean to keep odors down.
 
CR
[Posted in FML issue 3145]