Goldfish aggressively chasing each other

Hi Group,

I have three ryukin goldfish, and two of them are constantly
aggressively chasing the third one, which I just bought. I assume
that this is breeding behavior, but I'm concerned because it really
looks like the chased fish is going to be injured or killed, and if
nothing else, it seems quite miserable. Is the solution to isolate
the chased fish for a while, or something else? Thanks in advance for
any guidance.

--Larry