Schizophrenia typically emerges during adolescence, with progression from an ultra-highrisk state (UHR) to the first episode of psychosis (FEP) followed by a chronic phase. The detailedpathophysiology of schizophrenia and the factors leading to progression across these stages remainrelatively unknown. The current treatment relies on antipsychotics, which are effective for FEP andchronic schizophrenia but ineffective for UHR patients. Antipsychotics modulate dopaminergic andglutamatergic neurotransmission, inflammation, oxidative stress, and membrane lipids pathways.Many of these biological pathways intercommunicate and play a role in schizophrenia pathophysiol-ogy. In this context, research of preventive treatment in early stages has explored the antipsychoticeffects of omega-3 supplementation in UHR and FEP patients. This review summarizes the action ofomega-3 in various biological systems involved in schizophrenia. Similar to antipsychotics, omega-3supplementation reduces inflammation and oxidative stress, improves myelination, modifies theproperties of cell membranes, and influences dopamine and glutamate pathways. Omega-3 sup-plementation also modulates one-carbon metabolism, the endocannabinoid system, and appears topresent neuroprotective properties. Omega-3 has little side effects compared to antipsychotics andmay be safely prescribed for UHR patients and as an add-on for FEP patients. This could to lead tomore efficacious individualised treatments, thus contributing to precision medicine in psychiatry.