Fish oil caps usually contain 180mg EPA and 120mg DHA per capsule. This is standard potency. Buying capsules with higher amounts of EPA and EHA per capsule is what you want to do – Trader Joes, Carlson, Costco, NOW foods all sell good high potency capsules, which give you more bang per pill. As far as trusting what is in each pill or capsule, all you need to look for is the USP logo on the bottle, which tells you that the USP lab has tested the product to ensure it contains what it claims. For this reason, I buy $4 Wal-Mart multi-vitamins, which are guaranteed to be just as potent as the $30 stuff you might buy at a vitamin store. So figure out the potency you want and then buy the cheapest product verified by the USP. NOW Foods’ products are all USP, so I really like what they sell. Good prices too. I still prefer Carlson liquid fish oil, though, to capsules because I take such a high dose.