Gold sucking loach. My son had two in his tank ( lfs said they were good community fish ) one was such a bully to all the other fish we had to get rid of him/her. Now the remaining one is turning nasty as well. The red tail shark is terrified of him & hes much bigger.
Exodon Paradoxus - Bucktooth Tetras. They were sold to me as community fish and harrassed everything I had nearly to death. I didn't think they were all that cool looking on top of it.
I would keep any fish! I've even got over my fear of Discus!
I wouldn't keep a frog though I am deathly afraid of them. Whenever I see one, I just freeze up and cry.
One time there was a frog sitting on my front door (on the outside) RIGHT next to the door handle so I couldn't get in my house. I actually went through the back gate, through the back yard into my pool area and then inside through the sliding glass door.
Black SKirt Tetras. Also sold as a community fish.....but only if packs of 5 or more. Any less than 5, and they get aggressive; and eat my female betta alive!
Well... I've told myself that I wouldn't ever get Pacus again... but... I have a few of them... again... Long dumb story as to why I have 5 of them. I love them but they just get so damn big so damn fast! (the only fish that I found that not only keeps up with but out grows my Oscars!)
But God bless them because they are the reason I first started considering an indoor fish pond... which is happening.