[Peter Finke]

We had this strange behaviour with quite a few of the newly imported spec. Ampah too. Most certainly it is a special weakness of this population, maybe a special reaction to stress. There are populations that react much more intensely to stress than others.
We were unable to cure it by medicine, and some fish did not recover at all. Some others did, however, given best conditions (changing food, water with pH about 5, at least not more than 6, often partly changed, quietness, no disturbance, slightly elevated temperature). So I should try the same. I think you can do nothing else. It is for sure that some of our fish recovered from the same symptoms you have described, but – as I said – not all.