This is a book (novel) I read as a boy, so would have been published before 1970. Set in South (probably Louisiana), the boy and his dog paddle through the bayou on a boat (pirogue?) and fish for Gar. The boy has a sister; she is assaulted at one point by a young man from a bad family, but is rescued by a young man from a quiet and good family. The assaulting man is killed and the killing hushed up. Afterwards I think the girl and her rescuer marry. Later the boy goes into town and there is some mention of black superstitious practice involving (if I remember) putting something into a tree, then plugging it up.I tried AI but it was absolutely no help.Perhaps a Harper & Row publication. perhaps 1965.