What is wrong with my guppy fish?

I have a guppy who seems to have a damaged front fin. He is still swimming with the other guppies but isn't moving the fin that's damaged. I'm not sure if it's that the other guppies have nipped that fin or if it is a disease. He is fairly new to the tank and didn't have this when I put him in. Does anyone know what is wrong with his fin or what I should do? Guppies are naturally fin-nippers and if his fin was just nipped it should grow back and he'll be fine since guppies do this sometimes to establish dominance but I'm not sure if the fin should look whiter in color which makes me think it could be something else but I'm not sure.