I got 10 healthy RCS off ebay a few weeks ago and in the last 4 days or so they have been slowly dying. I have 3 left and I've done everything for them. The water clean and tested, tank's cycled, and the temp is 80 F. I have very young pygmy cory fry in there and they are doing great. We have well water and I've added no chemicals. Should i just give up and not get anymore once the rest die? I heard they were easy to raise but I'm not seeing it. Advice please?