Effects of different stocking densities on haematological, non-specific immune, and antioxidant defence parameters of striped catfish (Pangasianodon hypophthalmus) fingerlings reared in finger millet-based biofloc system.

Abstract

A study was conducted to investigate the efects of diferent stocking densities on growth, haematological, non-specifc immune, and antioxidant defence parameters of striped catfsh (Pangasianodon hypophthalmus) fngerlings reared in a fnger millet-based biofoc system. Striped catfsh fngerlings with a mean initial weight of 7.34±0.06 g were randomly stocked in triplicate at six diferent treatment groups, which included 150/m3 (T1), 180/ m3 (T2), 210/m3 (T3), 240/m3 (T4), and 270/m3 (T5) in biofoc-based units, and 150/m3 (C) with clear water in plastic crates (capacity 160 L) and reared for 90 days. Finger millet four was used as an organic carbon source with a 15:1 C:N ratio. After 90 days of rearing, signifcantly (p<0.05) higher, percentage weight gain (298.21±9.92%) and daily growth index (0.24±0.01) were obtained in T1 (150/m3 ) and lower values were recorded in T5 (270/m3 ). The antioxidant defence response, SOD, and CAT activity of liver and gill tissues were signifcantly (p<0.05) lower in the T5 (270/m3 ) experimental unit and higher in the T1 (150/m3 ) experimental unit. Blood indices, haemoglobin, total erythrocyte, leucocyte count, packed cell volume, and mean corpuscular volu me improved signifcantly (p<0.05) in BFT units with stocking densities (150, 180, and 210/m3 ) compared to other experimental units. Stress enzyme responses, serum glucose (74.88±4.48 and 77.15±4.67 mg/dl), and serum cortisol (59.64±4.62 and 60.65±3.11 ng/ml) values were signifcantly (p<0.05) reduced in BFT units (150, 180/m3 ) when compared to other experimental units. Non-specifc immunity responses such as nitro blue tetrazolium activity (0.41±0.02 OD at 540 nm), serum myeloperoxidase (1.08±0.05 OD at 450 nm), and serum lysozyme activity (51.40±2.02 U/ml) were signifcantly (p<0.05) reduced in T5 (270/m3 ). From the results of the present study, it may be concluded that a stocking density of 240/m3 (T4) is ideal for overall individual growth, better immune, and stress responses of striped catfsh culture in BFT system.