My goldfish is hurting my other goldfish?

emiandfish

New member
My little brother and sister have 2 fish, both goldfish.
One is brown, and one is gold.
The gold one has been injuring the brown one, very aggressively.
He/She has been biting off it's top fin and nibbling on it until it bleeds, and swims away when it gets "caught"
The fish have been chasing each other, the gold fish has mainly been the chaser, trying to hurt him.
But remember, it's the top fin that he's been biting, and the other fish is slightly smaller.
I'm quite worried. Should we separate them?
 
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