not quite sure what happened. I do regular water changes on all my tanks. I treat water in a bucket, cover it, then leave it to stand for at least 24 hours for my small tanks. One day I did a water change, and immediately all my fish started acting weird. Within minutes 2 zebra danios died, but that was it. I kept a close eye on them for 2 days, and then assumed it had been some kind of shock. After a few days, I checked my tank, and one of my bala sharks was covered badly in ich. Mind you, the previous afternoon there was nothing, and suddenly there was ich and a few dead neons. I started looking my fish over, and saw that all the baby jurupari were just as badly infested with ich, and rubbing themselves on rocks, while the other neons had some signs of it. My knife and loaches looked fine, but I didn't move them as not to infect another tank. I cranked up the temp, and added rid ich for a few days, but for some reason kept on losing a few fish a day. Finally my fish started stabilizing, and the two surviving jurupari were nearly free of signs of ich. I was sort of happy, since despite losing the bala sharks and a few neons and danios, my knife and loaches and surviving jurupari were fine. Last night, I inspected the tank again, and noticed my knife acting weird. I looked closer, and noticed white areas on his body. I did a large water change, but it didn't help. The water paramaters and quality was good, but he was getting worse. This morning, the white spread to 1/4 of his body, and he shortly died. A few of the white parts of his body were red, and bleeding a little. It was very weird.