Stocking density matters in open water cage culture: Influence on growth, digestive enzymes, haemato-immuno and stress responses of Puntius sarana (Ham, 1822)

Abstract

A 90 days trial was carried out to investigate the impact of stocking density on growth performances and the health status of Puntius sarana in inland open water cages (Salia Dam of Odisha, India). The fishes of mean body weight 32.04 ± 1.25 g were stocked @ three stocking densities (SD) i.e., 10 m−3 (SD10), 20 m−3 (SD20), and 30 m−3 (SD30) and fed with commercial feed of 28% protein and 4% fat. The growth, in terms of weight gain, specific growth rate, absolute growth rate, percentage survival, protein efficiency ratio, and feed conversion efficiency was significantly decreased (P < 0.05) with increment in stocking density, however the lowest feed conversion ratio (FCR) was obtained in SD10 (1.68 ± 0.02). At the end of the experiment, a significant increase in red blood cells, haemoglobin, haematocrit, and platelets level was found in SD30, while white blood cells were showed a reverse trend. The concentration of superoxide dismutase, catalase, serum glucose, serum glutamic oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT), and cortisol were increased significantly in SD30. On contrary, the level of serum triiodothyronine and thyroxine decreased with an increase in stocking density. The higher stocking density negatively affected the amylase activity without any adverse impact on protease and lipase. The cluster analysis revealed that SD20 and SD30 came under the same dendrogram while SD10 formed a separate one. The outcome of PCA (Principal Component Analysis) revealed that increased levels of SGPT, SGOT, glucose, and cortisol negatively influenced the growth attributes. Stocking density up to 20 fingerlings m−3 of P. sarana in inland open water cages performed ideally in terms of growth and health status of fish.