Depression is one of the most common mental health concerns of adults, but it has long been overlooked with children and adolescents. It has only been since the 1980s that depression in children and adolescents has emerged as an issue at the forefront of professional concern.

The primary characteristics of depression are excessive sadness, loss of interest in activities, sleeping problems (either sleeping to much or not enough), slowing of physical movements (in some cases physical agitation), lack of energy, preoccupation with death or dying, feelings of worthlessness or excessive guilt and difficulty in thinking, concentrating, or making decisions. One symptom commonly seen in depressed children and adolescents is a failure to make expected weight gains, as opposed to actual weight loss.

While awareness about depression in kids is increasing and medication can help treat the illness, a lot of children still suffer because adults don't realize they are depressed. Studies have found that eating fish could stave off depression (even postnatal depression), slow mental ageing and reduce risk of suicide. A report in the British journal, the Lancet in 1998, gave the details of a study conducted by Joseph Hibbeln of the National Institute of Health, which suggests that the consumption rate of Omega-3s found in vegetable oils, fish and shellfish is correlated to the rates of depression. It was found that there is a direct correlation to lower rates of depression in countries that consumed large amounts of fish. Hibbeln had also predicted the amount of depression in countries based on the amount of fish consumed by that country.