This morning I found two of my panda corys had passed. One was in full rigor, so passed within the last 24 hours, the other has shown signs of scavenging, and I would assume had passed 24-48 hours previously and ended up behind the plant where I found it.
I had a power outage 5 days ago and my ac70 quit. I grabbed a new filter, placed the filter media from my ac70 into the new filter to try and avoid a crash.
My parameters are Ph 7.6, Ammonia 0, Nitrites 0, Nitrates 20-40 (typically closer to 20, but for some reason has raised a bit), temp 25⁰c. Rooted and floating plants, no fake plants. Plenty of hides, and filter output is angled so the current goes across most of the tank to avoid dead zones.
I have 4 remaining corys that I want to make sure stay healthy. There is no redness on the stomach or gills, and the ones who passed were 2 younger ones I added about 2 months ago.
What could have happened to the two who passed? Everyone else in my community tank is healthy and active.