Previous studies have linked low levels of omega-3 to several neurobehavioral disorders, while rowdy British kids supplemented with omega-3s showed improvements in behavior and learning after only five months.
The new results show that people with low blood levels of eicosapentaenoic acid (EPA) docosahexaenioc acid (DHA) were more likely have mild-to-moderate depression (as scored by using the Beck Depression Inventory).
High serum levels of DHA were related to more 'agreeableness' while people with low linolenic acid (LNA) levels were linked to being more 'impulsive'.
Sarah Conklin from the University of Pittsburgh School of Medicine said: "A number of previous studies have linked low levels of omega-3 to clinically significant conditions such as major depressive disorder, bipolar disorder, schizophrenia, substance abuse and attention deficit disorder.
"However, few studies have shown that these relationships also occur in healthy adults. This study opens the door for future research looking at what effect increasing omega-3 intake, whether by eating omega-3 rich foods like salmon, or taking fish-oil supplements, has on people's mood."
Only last week a panel of experts the American Association for the Advancement of Science said that the benefits of eating seafood continue to outweigh the risks.
"The best science coming out over the last two years has overwhelmingly been in favour of the benefits of seafood consumption," said Michael Morrissey from Oregon State University's Seafood Laboratory.
Morrissey stressed that pregnant women should stick with current FDA recommendations of about 12 ounces (340 grams) per week. The rest of the population should be eating fish four to seven times per week.
EPA is proposed to function by increasing blood flow in the body. It is also suggested to affect hormones and the immune system, both of which have a direct effect on brain function.
DHA, on the other hand, is involved in the membrane of ion channels in the brain, making it easier for them to change shape and transit electrical signals.
The Pittsburgh results were presented last week at the 64th Annual Scientific Meeting of the American Psychosomatic Society.