There is emerging evidence that the supplementation of omega-3 contributes to a decrease in aggressive behavior in prison populations. The objective of this study was to determine if the omega-3 index is correlated with aggressive and attention deficit behavior in a prison population. 136 adult male prisoners were recruited from South Coast Correctional Centre (SCCC), NSW Australia. The baseline omega-3 index ranged from 2.3% to 10.3%, indicating that some participants already had substantial omega-3 intake, however a median of 4.7% indicated a lower overall omega-3 intake than the general Australian population. Assessment of aggressive and attention deficit behavior shows that there were negative correlations between baseline omega-3 index and baseline aggression categorization scores; total aggression score; Anger; Hostility; indirect aggression; total attention deficit disorder; Activation; Attention; Effort; Affect; and Memory. In conclusion, there is a high variability in omega-3 status of a NSW prison population, and inmates with lower omega-3 index were more aggressive and had higher ADD scores.