With all due respect, this is excerpted from a Brady Brandwood post:
Tosai stress easily so scraping them is truly crazy!!! Imagine the stress involved in this,... and also imagine the huge hole you've opened up in the slime coat with the glass slide from the scrape!!! Also, gill snips are barbaric! Bombarding them with chemical after chemical WILL kill them! USE SALT! We've had some sort of bad press lately proclaiming salt is useless,... it is very helpful, and very safe and effective. Use salt as a dip - 4 cups of rock or solar salt per 10 gallons of pond water in a Koi tub - put the fish in this dip for 30 seconds, then take it out and back into fresh pond water. Do this with any new fish before putting them into your quarantine,... and do this if you see your new tosai is not feeling well. This is a safe simple way to "fix" or cure most of the issues many have described here on the board.
The full text can be referenced at:
http://koiphen.com/forums/showthread...1&page=4&pp=10
Oh, it's post #37 in a rather long, rambling thread.