You did not kill the fish only to keep alive and to sell for food, he thought. You killed him for pride and because you are a fisherman. You loved him when he was alive and you loved him after. If you love him, it is not a sin to kill him. Or is it more?
And the lost heart stiffens and rejoices in the lost lilac and the lost sea voices and the weak spirit quickens to rebel for the bent golden-rod and the lost sea smell quickens to recover.