i need some advice my oscar previously had hith disease and i treated it but it took a little while because when he first had it the fish store told me it wasnt it until finally it was obvious and i said the hell with what they said and treated him for it and i was right he got better and now i presume he has it again it is hard to tell exactly if it is getting worse tho and he has a dime sized sore on his back fin and the pin holes on his head but have never seen the sore like that in hith i have had him in a quarantine 10 gal for 3 treatments of parasite clear the fizz tablets he got his first treatment and 25 percent water change after the 48 hours and then repeated for today his third treatment i am not sure if he is getting better tho because i dont know how to tell and since it was worse this time i dont want to chance not curing it all before putting him back also if someone could tell me i know it is controversial but anyone have a clue as to why they get this? i am strict on tank maintence because of the dirty fish i have and have a 6 ft tank 150 gal with the marineland canister c-360 and a magnum 350 canister filter both running all the time and i do 25 percent water changes a week and i run a complete water polisher on the tank aprox once a month to remove leftover debris in gravel that i cannot by wter changes alone. thank u for your help...