Hey group. Long story semi-short had 6 rummynose and 8 cardinal tetras in a 75g. Tank was cycled. I qt'd the rummies in a 10g for 6 weeks. Two weeks into the qt period, one developed a few ich spots, I immediately treated and went away quickly. I kept them in qt for another month after last sign of the ich.. all were fine no reoccurences. I then transferred them to the 75 with the cardinals. All was good for maybe 2- 3 weeks. One cardinal died, then slowly one by one started dying, lost a total of 3 cardinals and 3 rummies in about a week. Fish were showing no signs of any obvious disease. Water always 0,0,5-10 tops... Maybe one or two them isolated themselves and died shortly after. Been a week since last death. All are eating and acting normally except one rummy and he is getting very thin. Any ideas whats happening? What to do,next? I did remove a piece of driftwood that had long white fungus/algae and it smelled eggy. After I removed that they stopped dying...not sure if that mattered...Thanks so much in advance and so sorry about long post.