So for mine , it was a few months ago with my then younger Blood Parrots and a female Jewel Cichlid. I had went to my LFS and they had recommended me Jewel Cichlids as a tankmate for my BPs and that the female fish in particular was even more laid back than the rest and would be a perfect match. So, I got her and everything was going fine for a month or two. Then, she slowly started taking over the tank bullying my BP's into corners so she could eat all the food, claiming the caves that they had already established, etc. As I previously stated, my BP's were younger and only introduced to the tank a little over a month earlier than she was so they weren't as established and old enough to really protect their areas with caution as they do now , and defend themselves. It got so bad that she basically ruled the tank and the other fish stayed in corners. So, I removed her and put her into another tank to cool down and the BPs went back to normal. I decided to try it again and I put Trina ( The Jewel) back into the tank with them but I guess my BP's decided they we done with her and both of them proceeded to sneak attack her when she was eating and push her into the wall of the tank and constantly ram her swimming full speed. They seem to each have taken turns and the other guard the areas she could run to. She died the same day and I never tried this again.....