Kind of hard to tell from the angles...but, it does appear to be swollen....Since this is a new fish I would wonder if he brought anything from a parasite to a bacterial infection with. If it were me I would ensure the water is pristine and start a round of general cure by API, It maybe trauma as well from a move, what have you, but I would want to stop any possibility of a secondary infection. which general Cure should do as well.......D