The health benefits of oily fish such as salmon, trout, mackerel, sardines are well documented. It helps keep the brain active and alert, aids infant brain and vision development, helps lower blood pressure, aids in reducing inflammation, amongst many others; basically a 'super food'.
(http://www.salmonfromnorway.com/Fish-School/Health)
Consumers are increasingly aware of the importance of omega essential fatty acids supplements in their diets. Whilst there are many brands of fish oils available in the markets, there are also many with high TOTOX levels (lower levels are 'fresher') by using inferior raw materials with poor traceability. Furthermore, outdated methods of refining oils at high temperatures results in the conversion of good fatty acids from cis- to trans-configuration, which is known to raise the levels of 'bad' LDL cholesterol and lowering the 'good' HDL cholesterol.
A good fish oil incorporates good manufacturing practises, is extra virgin fresh, has full traceability to origin of raw materials, found in cold clean waters without environmental toxins, and does not come cheap! So eat well, but also eat smart.