banggai cardinals

aquapod 24

well i dont know if i have a pair or not. some times they are near eachother ans some times they are not, but they are mostly together... also, the "male" sometimes goes after the"female" and nips at her a little but i have only seen this happen a couple of times. is this normal for a pair to be moderatly agressave tward eachother occasionally? as i type right now they are under a ledge right next to eachother. so will only time tell if they are a pair or is it possible to make an asumption right now?