Thats an awesome rainbow you got there and i must say i have never seen a rainbow that dark before and never have i seen one with a dark line like that along its side. But i think it maybe a brood stock cause if you look at the tail it isnt pointy it's kinda boxy which tends to happen to fish that are raised in hatcheries cause they get too big and they wear their tails away on the gravel and concrete.But either way its still a beautiful fish. Good Job