do you have a quarantine tank? If so I would say net the clowns and add a copper based ich treatment. Your LFS should have them. You can also raise the temps in the quarantine tank to help your fish fight the ich with a water heater that might otherwise cook your shrimp. However, if you can't net them (I can't since my tank is large, my fish are wise, and too many cracks and crannies in my live rock) or you lack a quarantine tank I would reccomend buying the more expensive CopperSafe Rid Ich treatment. It's safe for invertebrates like your shrimp, corals (if you decide to get some), and bacteria in your live rock. I keep a bottle of the Rid Ich and full spectrum antibiotic they make in the cabinet of my stand. I've only had to dose once for ich when I foolishly didn't quarentine a new arrival. It didn't kill an invert and everyone seemed to recover quickly.