Aggressive/Cannibal Goldfish!?

I bought a black moor today and when I put it in my tank, my shubunkin started to chase it and nip at it straight away. It wont leave it alone so Iv separated them. But he didn't go near the other new one I got, an oranda. This has never happened before with any fish I've put in with him. What should I do? Will he be less aggressive if I put them back together in a few days?