Santiago states his two hands and the fish are brothers. What might this mean?

I think this illustrates the conflict Santiago has over the fish. He respects and identifies with the fish yet he has the hands of a fisherman meant to catch fish.

It will uncramp though, he thought. Surely it will uncramp to help my right hand. There are three things that are brothers: the fish and my two hands. It must uncramp. It is unworthy of it to be cramped. The fish had slowed again and was going at his usual pace.