There are non-fish oil omega-3 supplements out there.
Here’s a link to one, but feel free to google for alternative brands.
http://www.devanutrition.com/vegan_DHA.html
It’s probably flax seed oil.
There are a couple of problems, the beneficial fatty acids are not present in the flax seed oil and require bioconversion in the body which may occur at varying rates based on genetics.
The second is that flax seed oil is not that healthy for males. It is related to some health issues, prostate cancer I believe. I don’t remember now but I switched to fish oil when the study was published a number of years ago.
My wife still takes flax seed oil because she doesn’t like the after taste of the fish oil.
It was increased risk of prostate cancer that was the concern.
http://articles.mercola.com/sites/articles/archive/2004/07/21/flax-seed-oil.aspx
It made a great deal of difference in how I felt. Subscribing to the fallacy that if two tablespoons is good, four is better resulted in a day or two of an upset tummy - burping, so I cut it back and am doing fine. I'm actually losing weight (Saints be praised), and have dropped one dress size since starting a month ago. Just don't over do it. We also eat a diet rich in fish and poultry, vegetables and rice -- both brown and long grain white. I season with sea salt in moderation, garlic and other herbs. I'm having a ball -- so many things to choose from.