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I have a Yellow Clown Goby that I thought had ich, right after I introduced it into my main tank after a 4 week quarantine. It was doing what I considered "flashing" and seemed to be blotchy white on its body, like an overactive mucous coat. I *thought* I saw white specks, but wasn't sure. I put it back in the quarantine and treated it with hyposalinity. When I was researching treatment, I kind of remember running into an article that said gobies were more sensitive to copper treatment than other fish and you have to be even more careful than normal if treating gobies with copper. I think I'm remembering that right, and have the article bookmarked at home - I'll post it later today. That could be why you don't see them treated in LFSs with copper.
With the hyposalinity and an extra wait time, the fish was in the QT for another 8 weeks. I was waiting to see if anyone else in the main tank was going to have to joing him in the QT. No fish in the main tank showed any signs of disease at all. When the Goby was looking fine, I put him back into the main tank. Within a couple days, he was "flashing" again, and looked a little blotchy. Grr.
I decided to take a "wait and see" position and was happy to see the white condition on his body clear up. I also figured out that the "flashing" was just his way of kicking stuff up off the rocks and coral so he could eat it. I talked to a guy at one of my trusted LFSs, and he mentioned the same thing about the "flashing" - he'd seen that a lot and just considered it their method of forraging. He also commented that from his observations, Yellow Clown Gobies seemed to have "skin conditions" that kind of appeared to be velvet-like... but he equated them to stress. (They ARE high-strung little fish!)
Long rambling story short... the "skin condition" on my YCG eventually resolved itself, and no other fish have been sick in the tank. He still "flashes" to this day, but seems to be a healthy happy little guy. At the time, I thought it was ich or velvet. Looking back on it, I don't think it was either because no other fish showed any signs of disease.
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