Omega-3 fatty acids are essential for good health. Try to eliminate them from your diet by eating roasted or baked fish, not fried. Fish oil supplements may be helpful if you have high triglyceride levels or rheumatoid arthritis. Fish oil appears to contain almost no mercury, which may be a cause for concern in certain types of fish.
While generally safe, consuming too much fish oil can increase the risk of bleeding and affect the immune response. It's not clear if fish oil is safe for people who are allergic to shellfish. Take fish oil supplements under the supervision of a doctor.