The sooner you dip the more effective it should be, before the abundance of parasites in your tank grows. These parasites will still be in your tank when you replace the fish however. So it will be imporatant to keep the fish as healthy/strong as possible to prevent reinfestation. That means removing the causitive stress factors that may have made the fish susceptible in the first place. Could be as simple as one bath in FW, but if symptoms persist isolation and treatment with hyposalinity or copper (
Joyce Wilkerson believes copper treatment may lead to sterility in clownfishes though) would be necessary, those are the two most effective treatments for cryptocarion. Research the heck out of either one before you try it though, as they say, medicine is only medicine in the proper dosage.
Fwiw, in my limited experience, clownfishes generally withstand freshwater baths with no problem. Shoot for a minimum of three minutes, try for five if you can, some people even go longer but I don't know how necessary it is to go over five minutes. Make sure the temp and Ph match your tank.
What I will do is buffer the water, fill a specimen tank with it, hang it on the inside of the tank for fifteen minutes till the temp comes up, drop the fish in, time it, scoop him out into another specimen tank full of regular tank water for a few minutes, then release.
fwiw, ymmv,
chris
