Peace
Peace is a theme that is seen throughout the film and it relates directly to the river where Paul, Norman, and their father fly fish. On the water, they are disconnected from the disciplines, duties, and worries of their lives. Here they are able to be at one with nature, to be released from any hardships of their lives and simply be in a perfect moment where nothing is expected of them and nothing can be taken from them.
Debt
Paul is a young man who has the ability to become anything he sets himself too. We see that he is an artist on the river with his fishing rod. However, Paul has gotten himself into debt to the wrong people. Because of this debt, he is unable to live a life that is free from the constant threat that looms over him by these dangerous men who want their money. Paul's debt has robbed him of his freedom and eventually his life.
Haunted by Waters
Norman is seen as an old man fly fishing on the river at the end of the film. He says that all the people in his life are gone, including his wife Jessie and that he is haunted by waters. This is a major theme of the film as the meaning of A River Runs Through it is that the memories of his life are an ever-flowing current, like the river, that run through his heart and his mind. They are experiences that he must grapple and live with. Thus, Norman's narration of the picture tells us that this is his account of his life and relationship with his brother Paul. This story is the river that runs through him.