trying to ID movie involving fishing with 2 brothers (one possibly mentally challenged)

This is going to be a tough one because I barely recall the film and have few details. It came out between 5 and 10 years ago, and I think went straight to cable (HBO or Cinemax). Very gritty, set in the south.

I just remember that there were 2 brothers, one possibly mentally challenged and I think one dies at the end. There was some sort of legal intrigue. One brother had an odd name or nickname, something like Peabo, and I think it was the title too (nothing found by that spelling though). Much of the movie was set in a boat, on a swamp or river.

I know that’s not much to go on. I thought one of the actors was Guy Pearce but looks like I was wrong…