Heres a quote from someone regarding my frog spawn.
My understanding (from my Marine Biology days, it has been a few years) is that typically when clowns do this behavior, they are exposing their immune system to thier new host Nematocysts, which will cause their body to produce a slime coat that synthesizes a protein that matches the corals own, which keeps the coral's nematocysts from recognizing the clownfish, as a foreign body. In other words he should stop, but if he doesn't you might be fishing for a clownfish