Anybody have any experience with aggression in female RES's toward each other? I have 4 females (had a male, he was extremely aggressive toward the females---biting, etc, so I gave him away) in a 200 gallon pond.
Very recently, I noticed the oldest female has been biting the second oldest female on the edge of her shell just behind her head, who has begun avoiding her and spending less time in the water. This is new behavior---they have been tankmates for five years and are about the same size.
I think this is a dominance, or pecking order, thing. The oldest does not bother the other two, one of which is younger and smaller. My concern is if it gets messy with wounds, etc---I'm not concerned about their group dynamic as long as everyone is relatively happy and healthy. Any suggestions?

