I have two clownfish in my 29 gallon FOWLR tank. I have had these fish for the last 3 months without a problem. Lately, I have noticed that one of the clowns seems to be going after the other one. They are both the same size and were added to the tank together. It seems that one backs the other into a corner and then darts after him when he swims away. I also have a coral beauty and yellow goby with shrimp that seem to be neutral. Is this normal behavior?