Fish oil contains omega-3 fatty acids, which can reduce the risk of coronary heart disease and lower cholesterol, according to the Mayo Clinic. The two types of omega-3 fatty acids contained in fish oil are called DHA and EHA.
The omega-3 fatty acids found in fish oil have other benefits besides protecting heart health. For example, omega-3 fatty acids help to reduce swelling and pain, which might be why fish oil is often a useful treatment for psoriasis (a painful skin condition) and dry eyes, according to MedlinePlus. This source states that fish oil is an effective treatment for high triglycerides.