New Forktail Rainbowfish is missing a fin?

Hi I just got my 6 new baby forktail rainbow fish yesterday from Aquahuna and they arrived all alive and in ok shape. I noticed that only 1 of them is sort of missing his dorsal fin? I’m trying to see if it’s clamped but they’re so small (all of them are 1” or smaller) I can’t really tell. The others do have all their fins and look good. I don’t know if this is a female and that is why but just wanted to know if someone could point me in the right direction.