What can be done about a moderate size fixed hatial hernia?

Moderate size hiatus. Small to moderate hiatus hernia and do not need any surgical intervention, if you have symptoms, treatment is recommended 1 if you are overweight try to lose weight 2 avoid strees 3 you can use antisecretory drugs like pump inhibitors or h2 blockers if the reflux symptoms are severe and do not respond to meds may need nissen funoplication you need treatment for symptoms and prevent stricture esoph.
Depends. If you are asymptomatic it can be followed without having to be repaired. Most patients with significant hiatal hernias have reflux disease and are treated with antacids. On occasion, patients will present with chest pain that can mimic a heart attack and are found after study to have a symptomatic hernia or they can present with bleeding and should be considered for surgery depending on health.
Surgery. Hiatal Hernias can be fixed surgically if indicated.
Your choice. Hiatal hernias that are large can cause life threatening problems such as bleeding and gangrene i the stomach, but thankfully these are uncommon. They are also unpredictable. Most large hiatal hernias start as small ones, and sometime only cause symptoms after they have grown in size and been present for many years. When surgery is needed, patients are typically in their 70's & 80's, when riskier.