1. Seafood can protect from heart disease, as well as lower the amount of cholesterol in the blood because it is low in saturated fats and high in Omega 3.
  2. Can improve blood circulation.
  3. Eating more seafood can help prevent rheumatoid arthritis, a condition that causes joints to swell.
  4. Fish and shellfish contain retinol, a form of vitamin A, which can help keep the eyes bright and healthy when eaten regularly.
  5. Seafood contains many essential nutrients and vitamins including iodine, selenium, zinc and potassium, which are needed to maintain a healthy lifestyle.

Source:
Selfish: The Authority on Fish
http://www.seafish.org/eating-seafood/seafood-for-health/health-benefits