hi all been having a problem in my freshwater aquarium for sum time now i have been treating for velvet for months and it just don't seem to be going away,my fish have always been flicking and yawning for a long time and there fins look golden metallic kinder shiny, lately it seems to be getting worse i have been finishing treatment courses then leaving it for a couple of weeks then starting again and am wondering whether the parasites have become resistant i just cant seem to cure it any advice would be very much appreciated im at my wits end thanx