The anal outflow of yellow mucus and fishy odor is considered to be the result of the following situations: 1. Mostly considered to be internal hemorrhoids, especially when internal hemorrhoids are serious, there will be edema and congestion, and they will also come out of the anus with the stool, and may also be stuck in the anus. 4, there may also be anal fistula, perianal inflammation and other causes, the best can go to the hospital to do anal examination.