What is the recommended daily intake of Fish Oil (RDI):
Dr. Barry Sears (author of "the zone", the new york times bestseller) who has dedicated much of his life to studying the benefits of fish oil on himself, his family and his patients claims that as a basic rule, it is always recommended that you take the least supplemental fish oil that you need to maintain a state of wellness.
He instructs patients to use the following fish oil dosage, "Start with 2.5 grams of a pharmaceutical-grade fish oil (What are Pharmaceutical-Grade fish oils?) every day. See how you feel after about 3 weeks, and then adjust your dose upward in small increments. If you continue to see a significant benefit in your mental and physical performance as you increase the amount of fish oil, your body needs a higher dose. Once the increase in benefits levels off, you know you've found the optimal dose and you can stop increasing.
If you don't see any changes after you increase your initial dose, try going in the other direction by reducing the dosage until you observe a drop-off in your mental or physical performance, or deterioration in your blood chemistry."
If you're suffering from a specific condition (such as arthritis or heart disease) or, you're at risk of getting a condition (due to either family genetics or personal circumstances), there are different recommended daily intakes for each condition.
Alternatively, you can always use blood tests to give you a more precise definition of your need for fish oil.