I know this is an old thread now but was reading my notes i made in relation to adding fish into my tanks.
The Cory that died i am convinced was the carrier of the problems i am battling with right now. He died within a week or 2 of adding him & i have had a parasite ever since, Just not as advanced, It has taken a while to diagnose the problem,So as i didnt know what i was treating i didnt use anything & all the time the problem has been getting worse,Also i didnt quarantine the new fish so its my own stupid fault
Lessons learnt here........Quarantine new fish & dont take LFS chat as the truth