Abstract: A study was conducted to evaluate the effect of different stocking densities on the growth performance of Tire track eels (Mastacembelus favus) in RAS to advise the farmers to adopt this technology of eel culture. This study was divided into two phases: nursing and grow - out phase. In the nursing phase, M. favus eels with the initial weight of 0.005 g were stocked at the densities of 500, 1000, 1500, and 2000 eel/m3 in the culture tanks of RAS. Feeding was done with Moina and Tubifex twice a day up to satiation and nylon substrates were placed for the hiding purpose of the eel fry. The highest survival was in the stocking density of 1000 eel/m3 (71.44%) and the lowest was in density of 2000 eel/m3 (56.44%). Statistical analysis by One - way ANOVA showed that there is a significant difference in the weight gain, length gain, DWG, DLG, and SGR among the treatments (P < 0.05). The stocking density of 1000 eel/m3 showed the highest growth. Similarly, for grow - out phase, the tire track eels were stocked at 100, 200, 300, and 400 eel/m3 with an initial body weight of 4.43±1.232 g. Feeding was done 2 times (8 AM and 5 PM) per day manually at satiation level for all treatments using commercial pellet feed (Micro 80) containing 42% CP. The growth parameters were not significantly different in all treatments (P > 0.05). FCR resulted lowest with the value of 0.94±0.12 in the highest stocking density treatment (400 eel/m3). The best suitable stocking density was found to be 1000 eel/m3 for the nursing and 400 eel/m3 for the grow - out of M. favus in RAS. Based on these findings, it is clear that stocking density highly influences the growth performance and the survival of M. favus in RAS. 

Keywords: Mastacembelus favus, Tire Track eel, Stocking density, RAS, Growth performance, Survival rate