Yes, it could be food aggression in that he wants all of the food for himself. Or, another viable explanation may be that something bad happened and he is trying to protect her from people. We are not really sure, but as long as the aggression is very limited and no one gets hurt, we don't think that it is something to be overly concerned. If the aggression turns into such violence that the female is seriously hurt, then you would either need to keep the pair separated during feeding. A way to do this is to keep him preoccupied with food being thrown toward him and have another person lead her away from him to a safer area to be fed. This may only be 10 feet or more, but could help alleviate the behavior. The Regal Swan