I have two oranda goldfish, 4 inch and 5 inch in a 24 gallon tank. ( am going two place in a 55gal when cycled). My largest oranda which I think is a female is nipping at the wen on the smaller fish which looks to be male. It has damaged the wen a bit but now I have a tank divider in place but I have been unable to remove it without the nipping starting right away again. Is this normal behavior and what do I do now?