Effect of Larval Density on Glycogen Level, Histology and Survival of the Freshwater Lobster Larvae (Cherax quadricarinatus) in a Recirculation Aquaculture System

        Stocking density is a key factor influencing both the productivity and well-being of fish in aquaculture. This study aimed to analyze glycogen levels and to examine the histological appearance of the hepatopancreas and muscle tissues in freshwater lobster larvae (Cherax quadricarinatus) at different stocking densities. The larvae, aged seven days after release from the maternal brood pouch, had an average weight of 0.02g and a length of 7.3mm. Freshwater lobsters were cultured at low, medium, and high stocking densities of 3, 6, and 12 larvae per square meter, respectively, for seven days in a recirculating aquaculture system (RAS). Results showed that glycogen levels decreased as stocking density increased: 0.108% at 3 larvae/m², 0.101% at 6 larvae/m², and 0.085% at 12 larvae/m². This indicates that higher densities result in reduced glycogen reserves. Histological analysis supported these findings. At stocking densities of 3 and 6 larvae/m², the hepatopancreas exhibited uniform, normal cells with organized lumens, and the muscle tissue appeared compact and healthy. In contrast, at 12 larvae/m², the hepatopancreas showed signs of cellular damage, including irregular cell shapes, non-uniform cell sizes, and disorganized lumens. Muscle tissue at this density also appeared loose and less structured. Survival rates further reflected the impact of density: 76.66% at 3 larvae/m², 80.83% at 6 larvae/m², and a significantly lower 45.41% at 12 larvae/m². Water quality parameters remained stable across all treatments during the experimental period. These findings suggest that the optimal performance of freshwater lobster larvae after seven days of culture was achieved at stocking densities of 3 and 6 larvae/m². The RAS method proved effective and could be applied to optimize rearing practices, enhancing both resource efficiency and profitability in commercial hatcheries.