Aggressive fish

I'v had my black moor in quarantine since xmas because of severe fungus and finrot, now he is very healthy again and I tried to put him back with his old tankmates and he suddenly started attacking them, really trying to rip their fins off.. he wouldn't leave them alone for 1 second so I took him out. I'v tried 3 more times but he acts the same..

1: why is he doing this to his old tankmates??

2: how can I stop it? or will he be solitary all his life now

 

A couple of quotes from other forums ......seems that all black moors act like that

all black moor act like that. active and aggresive, nothing to do
> with the shop where it came from. Just like you, i had a black
moor
> for about a month or so before i returned it to a shop in exchange
> for goldfish food and medications. My moor was bullying my other
> fish and was hurting my pearlscale.
>
>
>
>
> ---
> >
> > I had a black moor named Othello as well! He came from a shop
> where he was crowded and learned some unruly behavior and didn't
> stay with me very long...I took him back because he was bullying
my
> other male fish...