You should be eating fish. If you're not, salmon is a good place to start. It's tasty and full of Omega-3 fatty acids, which are essential fatty acids your body can't synthesize. In addition, studies have shown that eating fish is associated with a lower risk of depression (meta-analysis: Li 2016).
This is a simple and delicious recipe. I won't copy anything from Chef John here, just watch the video or read the blog.