So maybe about a week ago I got 2 firefish and a skunk cleaner to my nano and thought I'd be fine. My tanka possum wrasse was breathing heavy a bit later I'm not sure how long ago from the addition maybe a few days to about a week. And the day after that I found it dead in the tank outside layer of skin gone. Like white fish meat and bones. I did a water change the day before because I thought maybe the biofilter was having trouble with the additions so I did like a 50% change. Tested the water before the change it was at like 40ppm nitrate. The wrasse lying around on the rocks when I saw it breathing heavy and only moved if I stuck my hand in and touched it. Other than that it wasn't swimming much. Is it like ice or velvet I don't think they're might've been a few small spots on it. Not entirely sure. Does anyone know what happened and or what I should do?