•Fish growth performance of Asian seabass and water quality were analysed in IMAS and OAS without mangroves.•Fish biomass and survival were higher in IMAS than those in OAS without mangroves.•Fish performance was attributed to better water quality of integrated mangrove-aquaculture system.•Integrating mangroves with fish farming is beneficial for better seabass fish survival and growth. The potential use of mangrove swamp for fish farming industry is not clearly known. Therefore, current study was conducted to assess the growth performance of the Asian Seabass, Lates calcarifer cultivated in integrated mangrove-aquaculture system (IMAS) and open aquaculture system without mangroves (OAS). Fish survival and biomass production were higher by 11% and 12.5% respectively in the IMAS than those in the OAS. The fish growth performance was higher in monsoon than that in other seasons. It was in association with water quality parameters such as, high levels of DO, chlorophylls-a,b, nitrate-N, DOC, TOC; low levels of light intensity, temperature (air, water), SPM, chlorophyll-c, nitrite-N, ammonia, total phosphate, reactive silicate, and POC; as well with moderate salinity. The water quality seemed to be favourable for growth and survival of the fish. Therefore, integrating the mangroves with fish farming of the Asian seabass is beneficial for better fish survival and biomass production.