so about 3 weeks ago I set up a 125. I used established sponges and an established ac110. I also hooked up a fluval can that had not been used in a mth so it wasn't for cycling but rather more filtration period. I started off with one medium sized IRshark and a pleco. about a week later I added a red tail cat. then a week after that I added 2 tiger shovels. then a few days after that added a gar. before I added fish, I checked my water and it was fine. ammonia was at a .25 but I just did a WC before I added the fish. two days ago I noticed all my fish breathing hard. the gar's scales were completely off like someone took a grader to it, the cats seemed to have blood by its fins, fins themselves were eaten away and their skin looked like a sun burn, just peeling off like crazy. I immediately did a 40% wc and added salt. halted all food. the next day not any better so I did two 50% wc that day, the next day the rtc died, by the envenging one of the cats died. did two more 50% wc and the final tsn died this am....I am extremely upset with my loss,...ayone have any idea what they died from?