One study involved 80 young people aged 13 to 25 with early symptoms of schizophrenia. Half were randomly assigned to take fish oil tablets for 3 months and the other half were given a placebo for 3 months. The researchers followed the subjects for seven years and found that only 10 percent of those taking fish oil tablets developed schizophrenia, compared with 40 percent of those taking a placebo. 
Subjects were given fish oil tablets for a shorter period of time. It did not produce a stable and significant effect.
 the researchers concluded that taking fish oil tablets may help prevent schizophrenia in adolescents.