Fiber. An anal fissure is a tear of the lining of the anal canal which exposes the internal anal muscle causing pain and bleeding. First, however must make sure this is what is actually the correct diagnosis. If so, the most important aspect of treatment is soften the stool with fiber and fluid intake and warm/hot water to relax the muscle spasm.
Depends. It depends on the cause. For most people, a stool softener (like miralax) is all you need. If its painful, you can use topical hemorrhoid creams to help with the discomfort. If you have crohn's disease, then it's important to make sure the crohn's is under control. See your doctor to get checked, because sometimes what seems like a fissure is actually a fistula which is much more problematic.