Tank has been going for 7 weeks. Have a damsel and 2 clowns. The one clown has good color and swims all over the place. He likes to play in the sand a lot but i noticed he sometimes does this odd thing where it looks like he is having a seizer. Just every once and a while though. I am not sure if it is some behavior??? I just added the second one and he is not doing it. Thoughts?