I have two regrets fish wise:
and both of these fish had to go to the LFS due to aggression with the fish they were with..
1. I had a very big (12 inches long and thick) banded leporinus with a beatiful orange red throat. I had him from a 1 inch baby that my ex GF had given me.. I had him for about 5 years when all of a sudden he got nasty...
2. same situation, only this time with a 6 inch distichodus sexfasciatus that my ex GF also gave me (when she worked at a close by LFS she used to bring me home fish all the time - damn I miss her LOL) that I grew up to be really big...and again, once he got bigger than everyone else, he got nasty..
I know these situations were beyond my control, but I still wish I had these big colourful fish!