I bought two clownfish from Doni at the same time. they were very small when I got them so they have been together for some time. They are both about the same size and all of a sudden one of them is just terrorizing the other, chasing it all over the tank, so much so that the chased one jumps into the surface skimmer to get away. I'm afraid that it is going to get hurt. I don't have an anemone in the tank, so they aren't fighting over that. some advice please?