Clownfish aggression

[Llorgon]

I have 2 clown fish in my 75 gallon tank. They are both juvenile and one is bigger than the other. I have had them in the tank since August with no issues. Today the bigger one has been chasing and nipping at the smaller one. Trying to chase it away from food and just generally being a dick. I found the smaller one stuck to the power head and anytime it moved the big one chases it. I have separated them for now, but is this normal for clowns?

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