Long story short... Noticed some white spots on my cardinal tetras about 3 weeks ago. Turned the water temp up, treated the tank with API and the Marineland brand ich treatments over the course two weeks. Did daily 25%-50% WC during treatment. All carbon removed out of filters. All in all, lost all 15 Cardinals, 6 tiger barbs, and 5 Sterbai cory cats. The troopers that made it are 1 tiger barb, 1 Sterbai and my Tiger Pleco!!! The cory seems super active and the Tiger barb has no more spots on him and is starting to swim away from the corner he has been stuck in for a few weeks. His tail is in bad shape, but he seems to be swimming better everyday. The pleco was spotted with white dots VERY BADLY and is completely cleared now and seems active and back to his shy self!! How long should I wait before introducing new fish to the tank? I know the cory wants his friends back, but I want to make sure everything is cleared up. What would you do?? P.S. I bought the Cardinals from liveaquaria three weeks prior and they were the first fish to show the spots, so I think they were the ones to infect the tank. It really sucks because the whole tank was getting along so well. The barbs were being good!!