Another purpose of this study is to test whether adding fish oil will improve the benefit of clozapine and/or limit some of the unwanted effects of clozapine, compared to not adding fish oil. Fish oil is a medication used to reduce levels of some fats (triglycerides) in blood. Some studies have found that adding fish oil reduces psychosis (voices, suspiciousness). However the FDA has not approved fish oil for reducing psychosis, so for this study the use of fish oil is investigational. This study will test whether fish oil can help people with schizophrenia or schizoaffective disorders have less psychosis. Fish oil is not an antipsychotic medication.