So, i've kept TONS of fish those of you who know I even keep goldfish ponds and a silver arowana. I recently took two very small oranda goldfish inside and kept them in a 10 gallon tank from one of my ponds because they were small and getting pushed around. Yesterday they were perfectly healthy, eating their veggies, and all the water conditions were exact the only problem was they recently had ich but there was only minor signs left and I was treating the water with Seachem stress coat to keep the slime coat healthy so the ich couldn't come back and prime to prevent ammonia with my daily water changes but nothing else. Today I get home and they have shredded fins from what i think is fin rot, covered in ich, and they have small but deep holes in their head but around it is black. They had been doing wonderfully and growing well for two weeks without a problem and I didn't change the routine. WHAT HAPPENED????? And most importantly how do I keep it from doing it again???