1. I had a nice 3inch ornate bichir, very active and a beautiful pattern. I went to feed him one night and noticed he wasn't in his normal haunts, I figured he just found a new hiding spot and was waiting for lights out to come out, well two days go by and I decide something is wrong, I look behind his tank to find he was able to jump out of the tank and slowly became ornate jerky :C I was so sad because I could have saved him if i had only looked when i noticed he was missing.
2. I had a tank that was going perfectly fine, then one day i decided I anted to get something new for my fish to snack on. I went to my lfs and got some cheap Ghost shrimp and threw them in, The fish loved it and ate them all up. A few weeks later my girlfriend and I are watching the tank and she asks me "whats that coming out of that fishes butt?" I laughed and said "poop." Well i took a closer look and saw little red worms coming out of their butts. I found out it was callamanus worms and tried everything i could to cure the tank in the end all the fish died. :C