A Study of Omega-3 as a Treatment for Major Depression

Inclusion Criteria: * Must meet DSM IV criteria for non-psychotic major depression lasting at least 6 weeks or dysthymia. * Must be under the care of a mental health practitioner. * Must be able to give informed consent. * Must be able to attend the Black Dog Institute. Exclusion Criteria: * Unsuccessful treatment with more than 2 antidepressant medications (at therapeutically adequate doses and duration. * History of psychosis or mania/hypomania or personality disorder. * Non-English speaking or otherwise unable to provide historical information. * Having taken Omega-3 dietary supplements in the last 3 months. * Taking antidepressant medication for depression. * History of allergy to n-3 PUFA supplements, finfish or shellfish. * Pregnancy, breast feeding or planning to become pregnant during course of study. * Post-natal depression. * Current drug or alcohol abuse or dependence or history of abuse or dependence over the last 12 months. * Unstable thyroid function * Hepatic or renal impairment or other medical conditions that may interfere with the absorption and metabolism of omega-3 polyunsaturated fatty acids. * Coagulopathy or anticoagulant treatment. * Patients who, in the investigator's judgment pose a current serious suicidal or other safety risk, or patients who are not likely to be able to comply with the study protocol.