Don't know why you didn't ask me. I'm just the owner of a crayfish hatchery. You're right about avoiding copper at all costs when it comes to inverts. Here's some treatment protocols that will work on crays:
A salinity change bath of 10ppt for a minimum of 30 minutes (60 minutes preferred) will cause most ectoparasites to dislodge from the host crayfish.
A formalin bath, using agricultural-grade formalin, at a rate of 1ml per gallon for one hour will eliminate most bacterial and fungal hitchhikers from the cray's exoskeleton, thorax, abdomen, gills, and glandular ducts. Some formulin will also be ingested and will kill many parasites within the digestive tract.
Continued treatment for internal parasites can be achieved through the use of garlic extract additions to the cray's food.
The treated crays should be observed for 4 days for potential viral attack. If a virus is suspected, the crays need to be euthanized and the tanks and equipment sterilized to prevent the spread of possible crayfish viral plague.
