My 4" male salvini in my avatar terrorized 2 severums that were much bigger than him... I gave em away not too long ago for that reason, along with his smaller sibling. After they were gone he was very stressed (I had to net all of the fish out of the tank) and started getting bullied by a smaller female Blue Acara... he's still not as aggressive or colorful as he was before but he's getting better every day... my plan is to breed him with that small female next to him in the picture but she's still not mature.
I'm sure your salvini will rule that tank once he grows a little more, just give him a couple months.