I find this thread to be very amusing.
Pics do not do this fish justice, he was a great eater 3 worms a day.
When sold last week he was now a solid 8in and I am sure he will develop into a nice super red. Perhaps you were lokking too much into this purchase and should do some more...
I would do as motoro suggested and also up your regular water changes to atleast 40% a week with a thorough gravel vac.
I dont think that these infections are only introduced, they could come up from poor water quality ie lack of water changes