seek the problem and cure that rather than ignore the problem and try to cure the result. By that I mean a lot of people get HITH cos poor water, usually cos they are over stock and can't maintain good conditions without daily water care.If you are not keeping your nitrates below 40pph wk after wk month after month you need a larger tank or less fish. if you are keeping your water pristine but are still suffering HITH then seek out what may be a cause of stress, bullying is a common factor. again it comes down to over crowding or choice of fish. select tank mates carefully. lastly HITH isn't clearly researched so we are not fully aware of all the factors that cause HITH. But if you don't maintain the points I have high-lighted above you are very likely to get HITH. It goes without saying that you should also be maintaining a good environment suitable for the fish you intend to keep. temperature, diet, lighting or lack of it, all should give your fish a quality environment close to what the fish comes from or at least suitable it can live in.
I am not saying you have not done all the above, and I am aware that some members have taken on rescued fish already with HITH, but i want to make clear to you and other readers just some of the reasons HITH is present in your fish. It don't need to be, i don't consider myself a expert but do have many yrs in fish keeping and none of my fish have HITH and are in genral good health.
lastly I would consider octozin as a treatment if you recieved the fish with the problem, I would use a small hospital tank as cost of octozin isn't cheap as delboybully also pointed out. if you recieved the fish in good health I would forget treatment and consider all the above first. Remove the cause is the treatment.
