koi carp and tank mates

Question
my shubunkin and goldfish keeps really having ago at my Israeli koi chasing pecking and knocking him I'm worried

Answer
Adam,                                                               Since the goldfish are doing well together, you should remove the koi.  Koi are actually a pond fish therefore require a large tank. I suggest at least a 50 gallon for the Koi alone as they can grow to be VERY large. I hope this helps.