Woke up this morning to a dead panda cory. All was fine last night as I watched them before I headed to bed. Had them about 4 or 5 months now, bought them in a pair. The other one seems fine and is rummaging about on the bottom as normal. Havent done anything different or added anything, just checked my water and Ammonia = 0, Nitrate -= 0, Nitrate = 10 and ph 7.4. Temp is constant 24/75 degrees. This is my first casualty since getting my bigger tank and its upset me and my children because the panda's were our favourite fish. Is it just one of those things or am I doing something wrong. If they have a high mortality rate then I dont think I will replace him and look for something a little more long living to avoid sad faces!!! Just to add I do a 40 litre water change and gravel vac once a week, rinse out my filter media every other change and change one media element every 4 weeks. Feed the fish on variety of Flake, Frozen bloodworm, Catfish pellets, Algae wafers and Tubiflex.