I had one...returned it to the lfs after about two weeks. The first week he was a sweetheart, seemed more scared and shy than mean. Which is what the label on the lfs tank said he was...I should have listened lol. By week two he started coming out more and playing with the royal green terror that I had (which is also a fin nipper). Then I came home from work one day and found him mouth deep in the side of my blood parrot, literally eating her guts out! So I'd suggest keeping it with similar sized fish with a similar aggression level....and nothing too expensive 