Usually they are torn from unexperienced netting or from transport. In all cases that i have witnessed the fins grow back to a nice uniform shape. I would get him and just add salt to the water to help him out with healing.
bought mine with niped fins as he was in with other bigger fish, put him in the tank, kept up the water changes and fed him well and all is good now. Fins fine and growing well. He should be fine. Only thing i have noticed is if you put him in with bigish fish ( mine is in with a baby oscar and baby aro), the bigger fish sometime mistake his tail movemove for food. He isn't damaged but he has been nibbled now and then!