While it remains unclear exactly how eating lots of fish impacts your mood and risk of depression, the researchers said it likely has something to do with omega-3 fatty acids, which previous research has shown to affect neurotransmitters in the brain like dopamine (rewards center) and serotonin (happiness). There's also a chance that people who eat a significant amount of fish maintain more nutritious diets and potentially live healthier lifestyles -- we'll just go ahead and assume all those fried fish n' chips don't count here.
However, the study notes the 17% reduction was only seen in the studies that were based in Europe, but not the studies from other continents. This may sound fishy, but researchers said this could hinge on how these studies classified what constituted fish, what type of fish the people consumed, and how it was cooked. Ultimately, more research needs to be done, they said, but suggested chowing down on some fish may be a simple measure to reduce the risk of depression, according to the report.