Hi, folks. This is my first post in here, though I've come here a number of times and consider myself moderately experienced in caring for freshwater fish. I have a 33 gallon tank stocked fairly heavily with a variety of tetras and a few small catfish and loaches. I can provide a list if needed, but I probably have a dozen or so species in there. Anyway, about 14 months back, I added a couple African Dwarf Frogs. I had never heard of Chitrid, but the store sent them with a 10-day guarantee and I added them to my tank. They seemed fine for a while, but around day 15 one of them died. I attributed this to the fact that death is not entirely uncommon when dealing with commercial fish. The other ADF started acting funny, shed a layer of skin, and then thrived ever since. Until last night. Here's where the adventure begins. A couple months ago, I added several fish. A couple guppies, and several smaller fish (zebra danios, harlequin rasboras, and a few more neon tetras) and the two aforementioned loaches. I was careful of the nitrogen cycle and had gotten comfortable using the Microbelift bacteria regularly (the only one I've found that biologically handles nitrates as well as nitrite, it smells terrible). I was careful about weekly water checks, and was happy to see nitrites consistently at 0, despite all the new stock. Nitrates were harder to tell, because the test strips didn't seem to be the normal color even before dipping in water. Foreshadowing... About 5-6 weeks later, the guppies started dying, one by one. They each started to show signs of stress a couple days before, but water strips all looked great: zero nitrites, indeterminate amount of nitrates due to the weird color on the strips. I continued the regular doses of bacteria, monthly filter changes, and only minor water changes. About 9 days ago, as a treat for my son, I bought two more ADFs. Still ignorant of Chytrid, we added them to our tank. The new guys were considerably more active than their older cousin. Over the past week, we lost two of the zebra danios. It was very sudden, no obvious signs of distress. But, I decided to stop wondering about those nitrates and got a fresh pack of test strips. Lo and behold, nitrates were at the highest level indicated, despite all other measurements looking absolutely perfect. Old pack of test strips is in the trash. So, I took drastic action. I immediately did a 50% water change, and doubled the regular dose of Prime water conditioner in the new water. I also added a full-tank dose of bacteria. The next day (yesterday) I measured again, finding the nitrates at the high end of safe, so I did another 50% water change to ensure we were well into the safe zone. This time, the Prime conditioner in the new water was about 110%. Once again, I added a full-tank dose of bacteria. Over the past several days, all the ADFs became much more active, floating around "spaceman" style and then swimming around. One of them seemed to be trying to get out of the water, all of them spent more time than usual floating at the top. We thought they were having fun. This morning, all three ADFs were belly-up at the bottom of the tank. Since they like to stay still in a "play-dead" fashion, I thought they were just goofing around. But when I noticed it was all 3 at once, it seemed a bit too suspicious. I'm afraid I lost them all. So... the investigation begins. Was it chytrid? Stress from the 'trates? If Chytrid, what kind of decontamination would I have to do to make this tank safe for any new ADF in the future? And is that even possible without harming all the fish? These forums are filled with experienced and caring people, so I look forward yo your insights and advice.