Biofloc technology is a technique of enhancing water quality in aquaculture through balancing carbon and nitrogen in the system. The technology has recently gained attention as a sustainable method to control water quality, with the added value of producing proteinaceous feed in- situ. The present study was conducted to compare the effects of in-situ produced biofloc and externally added biofloc on the growth and production of rohu under different stocking densities Experiments were carried out in twenty seven cemented tanks (700 L each) for a period of 90 days. The experimental design included in-situ biofloc, externally added biofloc and control treatments conducted at three different stocking densities (STD) - 1.3, 2.6 and 3.9 denoting 1.3, 2.6 and 3.9 no. fish m-2 of surface area of tank respectively with each experiment replicated thrice. Mixed sex rohu (Labeo rohita) of individual average weight 50 ± 1.6 g was reared in all treatments. In in-situ biofloc treatment, low protein (20%) commercial fish feed was added initially. Further, organic carbon in the form of wheat flour was added daily to maintain the C:N ratio at 10. The amount of feed and extra carbohydrate required in biofloc process varies with time as biomass density varies with time. Around 60% extra carbohydrate to be applied in a typical in-situ biofloc tank. In externally added biofloc treatment, 50% of fish feed and 50% wet floc was added. The biofloc was produced in a 25 m3 cemented tank using aquaculture effluent from a nearby carp culture pond and maintaining the best C:N ratio of 10. In control treatment, high protein (30%) commercial fish feed was added. The harvested weights of fish in all treatments with different STD were found to be significantly different among each other (p < 0.05). Net fish yield was highest (2003 ± 24 kg ha-1 90 day-1) in externally added biofloc tank with highest stocking density (STD 3.9). Fish survival was 100% in all the treatments. The FCR values in in-situ biofloc treatment and externally added biofloc treatment were less compared to control treatment Fish survival was 100% in all the treatments. Frequency of water exchange was significantly less in externally added biofloc treatment compared to in-situ biofloc treatments and control treatments. The nutritional quality of biofloc was found to be quite suitable for Rohu. The images of 3-week-old biofloc captured in scanning electron microscope (SEM) indicated the presence of different types of bacteria, algae, protozoa, rotifers, etc. in different sizes ranging from 10 to 100 μm.