Hello my name is Varsha and I recently joined this community. I need a bit help understanding my parents aquarium environment. My parents recently got 2 gold fish and 2 koi fish I suppose. They added them to one tank with black moor fish. Within 1 hour, black moor fish started chasing koi fish. I'm not sure if it started to attack it or not but we separated koi fishes to other small pot. Can anyone help me with black moor behavior? I thought black moor are suppose to be non-aggressive