Yellow tang help!

I've had a yellow tang for three weeks. He's been great: eating like a pig and really energetic.

Yesterday it seemed like he wasn't as hungry. Today he isn't really interested in food at all. He's lethargic- just swims around slowly and hides more than normal. And he's really working his gills. It seems like he's breathing heavily.

I just put two snails and three hermit crabs in there...I hope I didn't introduce some parasite into the tank! One snail died and I removed it.

My tank:

55 gallon

1 margarita snail
3 hermit crabs (one unaccounted for)
1 ocellaris clown
1 yellow tang (the one in question)

Amonia- 0
Nitrite- 0
Nitrate- around 5
SG 1.025
Temp: 80 (a little high)

Any suggestions? Should I give him a freshwater dip? Does he sound sick? Do tangs just have weird appetites sometimes? but if so, why the labored breathing?

Thanks...I'm really worried.

Thanks for your response.

My PH is 8.3

I guess I wondered about the parasite since I just put those 5 inverts in the tank.

I'll keep an eye on him over the next couple of days...hopefully he'll turn around.

Yes, he was skinny when I first got him but I fattened him up and he was doing great for the last two weeks.

Thanks

This morning I got up and my ocellaris clown was basically laying on the bottom and acting weird. When I turned the lights on I saw he had Ich spots.

The tang's white stripe is bright and he's still not eating.

SO...I put him in the quarantine tank (10 gal.) and added methylene blue. I gave the clown a freshwater dip for about 20 seconds (he got stressed but seems o.k. now) and the rockwork is messed up in my tank from trying to get the tang out. ARGGHH!

What should I do? Should I assume it's Ich (like I've assumed so far)? If it is, do I have to leave my main tank empty for 2 months to have the Ich die off completely?

I can't think of any other reason the tang and clown would quit eating, breathe heavy, and become sluggish.

Thanks.

Thanks. Questions about that:

1) I don't see any actual spots on the tang (he's just acting like ich) Can you see Ich spots on a yellow tang?

2) How should I treat him? I've got methylene blue in the water and I'm going to lower the specific gravity to 1.012 or so.

3) Does methylene blue contaminate a tank for future inverts like copper does?

Thank you!

With hyposalinity, should I buffer the freshwater with baking soda like Robert Fenner writes in "Conscientious Marine Aquarist"?

Are you saying that I should put my two fish in the hospital tank for a month so that the Ich will die off out of the main tank? That sounds risky: my hospital tank is small.

Thanks for your help

One more question, how do you guys get pictures under your screen names?