Well I am sure it has happened to others and I am sure everyone has lost a fish, but our tank has only been up for a few days and this was my first one, and it was one of my favorites.
It wasn't from bad water parameters or any such thing, and it was my fault. Turns out we had a death trap area where one of our circulation jets blows right into this small crevice in a piece of our driftwood. It looks like after I did my water change yesterday and turned the jets back on, he was in front of a jet and was blown right into the crevice and could not back out. I didn't find him for hours until I was desperately looking for the whole group (with one missing) and finally noticed his little tail sticking out of the crevice
Death trap area is fixed (strategically placed rocks) but I was so sad and I feel so terrible
I cried. He was one of my favorites (Puntatus Cory)
RIP little cory, you were the cutest of them all