I had two male dwarf gouramis in my tank up untill this morning for a couple of weeks i noticed they have gone very skinny and are not eating. Woke up this morning and the healthier looking one had died, showed no obvious external signs of illness. The other one is not looking too good now it has been resting in the weed for a day now and is not eating not even bloodworm. I have treated the tank with melafix for the last two days. Anybody know what could be wrong. I have lost 5 fish in two weeks not from the same tank though i am not having much luck at the moment.