mine has grown very slowly as well, but parasites have never been an issue . . . I think the key was that he was sharing his grow-out tank with other fish (first one female convict, then another), and I think he wasn't aggressive enough to get his fair share of the food
now that he has the tank to himself, I'm starting to see a bit more development, he has certainly filled-out more
now that he has the tank to himself, I'm starting to see a bit more development, he has certainly filled-out more