Part of the study will be a 12-week parallel-group placebo-controlled double-blind randomized n-3 fatty acids add-on combination therapy trial. A total of 30 patients in the acute depression stage of bipolar disorder will be collected from outpatient clinics and randomly assigned to receive n-3 fatty acids or placebo. T-test (or Mann-Whitney U-Test) will be used to evaluate the differences in the severity of depressive and manic symptoms between the two groups across the study points. The second part of the study will be a 6-month add-on prophylactic trial with parallel-group, double-blind random allocation to n-3 fatty acids or placebo groups. A total of 31 patients with stable bipolar disorder recruited by newspaper advertisements will be recruited and randomly assigned to receive n-3 fatty acids or a placebo. Kaplan-Meier Survival analysis will be used to evaluate the differences in the recurrence rate of bipolar depression between the two groups. Also, t-test (or Mann-Whitney U-Test) will be used to evaluate the differences in the severity of depressive and manic symptoms between the two groups across the study points. The 2 separate studies will be conducted after approval from the Human Trials Committee.