These days our diets tend to give us much more Omega 6 than we need and not enough Omega 3.
It is true that fish is the best source of Omega 3 - salmon, herring, sardines particularly. Flaxseed is excellent for the ALA Omega 3 content and also lignan. ALA is required by the body as well as the longer chain EPA and DHA Omega 3. Some of the ALA will be converted by the body into EPA and DHA.
It is very fashionable to take Fish oil and Krill oil for your Omega 3 but it is a good idea to question where this oil comes from. Fish eat krill which in turn have eaten plankton which consume algae. The algae produces the ALA and the krill and fish convert it to EPA and DHA - far better then to actually eat the fish for all round good health.
Of course, if one is a vegetarian or doesn't like fish a good alternative is flaxseed.
Read http://www.courtofthesilverking.co.uk/alternatives.html for more information.
Although one can have oil which appears to be the 'ideal' balance of Omega 3 and 6, in reality since your diet is almost certainly giving you ample Omega 6 and not enough 3, it seems a waste of time having a 'neutral' balance unless it is replacing an oil which is high in Omega 6, or saturated fat.
I don't know much about hemp but I believe it contains more saturated fat than flax does.