A few questins to the OP........
1. Why do you need O3FA?
2. Are you strict vegetarian? or eat non veg too?
3. If non veg food makes up your diet, how many times a week you eat nonveg? how many eggs you eat a week?
4. How much milk you consume?
5. What are habits you presently having? like tobacco / cathechu / beetle nut / alcohol / smoking?
6. Whats your age?
7. Whats your body weight?
If you can answer all question true to your heart, you will get your answers automatically.
Omega 3 fatty acids are nutrition supplements, but more useful to cancer patients or cardiac patients. Or to the persons having extra risk of these diseases.
If you thinking of taking 1 tin of these capsules will make you invincible to diseases or make your bady like Ranbir kappor or make your skin glow like Katrina Kaif then you have got a wrong prescription mate

.
If you food habits are healthy and contain enough amount of milk / fruits / meat / egg / nuts / vegetables and most importantly water then you are getting enough of all nutrients.
I hope above information has cleared your myths, stay away from commercial preparations.
Still if you are insisting on taking it, then a pharmaceutical preparation called GLACEX from GSK pharma is good also contains additional vitamins. Its costly (i think 10/11 rs per capsule) and yes its marked Red for non veg contents. I have been using it to good effect in my patients with tobacco abuse.
BTW the earlier link of wiki article is really enlightening.