Clownfish aggression

[DW79]

I have the same problem with the 2 clowns I have. Mine are fine all day, but as soon as the lights start to go out, the bigger one goes after the smaller one to the point that it hides under a rock so the other one can't get it. From everything I have googled about it, they seem to be working out dominence, but it seems a bit much for a pecking order. If you have found anything else out, I would be interested to hear