Keep your psychiatrist in the loop about your use of fish oil. From what I've read online, from various sources, and as you have written, the EPA/DHA ratio is the most important ingredient with Fish Oil intake. In conjunction with my use of Setraline, I've been taking 2 [300mg Omega3 (1200)] fish oil capsules since early October. I do feel better, however, I'm not sure if it's the fish oil, or if it's the uptake of Setraline. Other antidepressant users have reported similar conflicting views on whether they are gaining benefit from fish oil, but it really boils down to the correct dosage. This will be debatable from person to person, and likewise, the right brand is an issue too, because it appears the more expensive fish oil brands have more EPA/DHA content.
My new psychiatrist and I discussed the use of fish oil, and she plans to raise my intake, after I adjust to a raise of 200mg on Setraline. From the conversation I had with her last week, a larger intake of fish oil supplements (with the right brand) are preferable, however she and I will determine what that quantity is. My last doctor didn't really keep up to date with the fish oil studies, and that was a big turn off for me, so I found a doctor who did, and who also has a better track record in keeping up to date with the research on other supplements, outside the use of psychiatric medications, on mental health.