Sometimes you need two meds, keep an eye on the fish as i don't like recommending two meds in the main tank, if they seem to cope with half the dose of protozin gradually increase it to the full dose, good luck, also watch your stats as it may knock them abit.
I have used it twice now and all fish look fine, they have all gone mad chasing the bubbles including the sick cory. I've never had the air pump going in the tank before but I think I will keep it now as the fish love it.
He still is darker than the others but hopefully the meds this time will sort him out.
I have finished using both meds and the white patch on the cories back has cleared up.
He is still looking a little dark and I was wondering if I should just keep an eye on him to make sure he has recovered or use the myxazin for one more course?
Should be fine i have, it's not a powerful med, and he has had a bad bacterial infection, but he sounds like he getting better, as i think if you stop it he might go down hill again, good luck.