How do you reduce sibling fighting without constantly refereeing?

Some conflict is normal and is how children learn negotiation, so eliminating it is not the goal. What reduces it: avoiding comparison between children, which is one of the strongest drivers of rivalry and is very common in Indian families; giving each child regular one-to-one time, since a lot of fighting is competition for attention; and coaching them to resolve disputes rather than adjudicating every one yourself. When you do intervene, describe the problem rather than assigning blame. Physical aggression is the line where you step in immediately and without negotiation.