Evaluation of Biofloc Technology for Astacus leptodactylus: Effect of Different Stocking Densities on Production Performance and Physiological Responses

Abstract

The use of biofloc technology (BFT) in narrow-clawed crayfish (Astacus leptodactylus) culture for 45 days was evaluated by production performance and physiological status of crayfish. Four different stocking densities of crayfish were tested in BFT (20, 41.66, 62.5, and 83.33 individuals m-2). Water quality parameters were monitored to sustain desired levels for crayfish and biofloc management. The growth performance of narrow-clawed crayfish did not show any significant differences among the groups. However, the survival rate changed by the stocking density. Hemolymph indices represented by total hemocyte counts and relative abundance of hyalinocyte, semi-granulocyte, and granulocyte were not affected by different stocking densities. Overall hemolymph glucose and lactate levels of narrow-clawed crayfish reflected mild stress in response to BFT conditions. Hemolymph protein concentrations did not change by the stocking ratio in BFT. Hemolymph protein levels were in the normal range, indicating the healthy status of the individuals. The hepatopancreas histology was observed as a typical morphology for healthy crayfish in all stocking densities in BFT. Notwithstanding the relatively lower survival rate in higher stocking density of narrow-clawed crayfish, the results of the present research revealed that the adaptation of narrow-clawed crayfish to BFT conditions is promising for the crayfish culture.