Abstract: In a recirculating aquaculture system with single-lamp UV devices, experiments were carried out to investigate the effect of UV light on fecal coliform inactivation. The research results showed that UV intensity, recirculating flow rate and UV transmittance of water were three important factors for UV inactivation efficiency. It was found that the higher UV intensity, recirculating flow rate and UV transmittance of water made UV devices more effective. Based on the experimental data, a bacterial inactivation model of UV light for recirculating systems was presented and the first-order inactivation rate constant was found to be 0.0062 m2/J for UV inactivation of fecal coliform. Simulation results indicated that, for disinfecting microorganisms with a lower inactivation rate, increasing UV intensity was more effective than increasing daily cycle number. The obtained results could be used for design and operation of UV inactivation in recirculating aquaculture systems.