The experiment was conducted with three biofloc treatments and one control in triplicate in 500 L capacity indoor tanks. Biofloc tanks, filled with 350 L of water, were fed with sugarcane molasses (BFTS), tapioca flour (BFTT), wheat flour (BFTW) and clean water as control without biofloc and allowed to stand for 30 days. The postlarvae of Litopenaeus vannamei (Boone, 1931) with an Average body weight of 0.15 ± 0.02 g were stocked at the rate of 130 PL m−2 and cultured for a period of 60 days fed with pelleted feed at the rate of 1.5% of biomass. The total suspended solids (TSS) level was maintained at around 500 mg L−1 in BFT tanks. The addition of carbohydrate significantly reduced the total ammonia‐N (TAN), nitrite‐N and nitrate‐N in water and it significantly increased the total heterotrophic bacteria (THB) population in the biofloc treatments. There was a significant difference in the final average body weight (8.49 ± 0.09 g) in the wheat flour treatment (BFTW) than those treatment and control group of the shrimp. Survival of the shrimps was not affected by the treatments and ranged between 82.02% and 90.3%. The proximate and chemical composition of biofloc and proximate composition of the shrimp was significantly different between the biofloc treatments and control. Tintinids, ciliates, copepods, cyanobacteria and nematodes were identified in all the biofloc treatments, nematodes being the most dominant group of organisms in the biofloc. It could be concluded that the use of wheat flour (BFTW) effectively enhanced the biofloc production and contributed towards better water quality which resulted in higher production of shrimp.

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Thenusunimaculatus (Burton and Davie 2007)is one of the most important commercially exploited lobster species in India distributed throughout the coast. The declining trends and collapse of the sand lobster fishery has been reported from the northwest coast of India. A number of hypotheses have been proposed to explain the decline, but a lack of basic information on population demographics inhibits hypothesis testing. In this study, morphometric stock structure analysis of Thenusunimaculatus was attempted to discriminate the spawning population collected from five locations (673 specimens) during 2017-2019 along the Indian coast. Data was subjected to allometric transformation to remove size effect. The transformed data was subjected to multivariate analysis, such as Principal Component Analysis (PCA) followed by linear discriminant analysis (LDA) using R software. The first eight PCs cumulatively explained 73.97% of the total variance,wherein the first two PCs together explained 45.50% of the total variance. The accuracy (ACC) and misclassification rate (MR) of the linear discriminant analysis (LDA) model performed to optimize separation among different sampling locations were 0.70 and 0.30, respectively, which indicates clear overlapping of the stocks among different sampling locations.The accuracy (ACC) and misclassification rate (MR) of the linear LDA model developed to discriminatebetween the coasts were 0.74 and 0.26,respectively, indicating no apparent differentiation in the samples between the coasts. The results of this study revealed the presence of asingle spawning stock of shovel nosed lobster, T. unimaculatus along the Indian coast.The information will aid in the development of better holistic management strategy for the conservation of this declining resource.