Ocellaris Clownfish

[mmasuda31]

Ive had my tank running for about 1 month now. It had finished cycling in about a week. I added about 25 lbs of live, cured rock. It's a 28 gallon bowfront. Put in the protien skimmer after it had finished cycling. Ive been doing 10% water changes. I've got a damsel, peppermint shrimp, emerald crab, and some snails in there, and everything had been running great. I added a clown fish, some mushrooms, and frogspwn coral a few days ago. Sine then the clown fish has apparently lost its dorsal fin, and this morning was laying on the sand next to the toadstool, his skin is peeling off it looks pretty bad. I check my nitrates last night and they were higher than normal at around 20ppm. pH is 8.2 salinity is 1.0025 and temperature is around a consistant 78. Whats going on with the clown is he just diseased? When I bought him he looked healthy. but in just a few days hes gotten real nasty. Any ideas guys?