The Old Man and the Sea sea as a Characters?

The Old Man, Santiago could really be viewed as either a protagonist or antagonist. Protagonist is the obvious choice. We see everything through his eyes, and he is a wise experienced fisherman. He is a character we like. However, he could be viewed as an antagonist in the way that he loves the fish and respects it, and yet wants to kill it. He is determined to harm such a noble and beautiful creature that we wonder if he really is the good guy. It is possible that the ending is a result of his being greedy, but as he said he is a fisherman and it is his job to kill the fish. Can we really hold him responsible for this?