Effect of Duration of Stunting on Physiological Recovery of Stunted Milkfish Under Field Conditions: A Relevant Farmers' Advisory

A study was performed to explore the effect of duration of stunting on the physiological recovery of milkfish. Wild collected milkfish fry (weight of 1.25 +/- 0.03 g and length of 5.53 +/- 0.03 cm) were stocked in earthen ponds of 0.02 ha, in triplicate, for different durations of stunting, viz., 4 months (Treatment-1; T4), 8 months (Treatment-2; T8) and 12 months (Treatment-3; T12) and normal seed (Control; C). Post-stunting commenced immediately after completion of respective stunting duration. In post-stunting, fish stocking density was adjusted to 5000 fish/ha and was fed at the optimum level (3-5%). The study found that stunting and duration of stunting had significantly affected the physiological response and recovery of fish. Significant reduction in serum biochemical components were observed in T8 and T12 groups (protein- 2.23 +/- 0.05 & 1.55 +/- 0.32 g/dl; albumin- 1.32 +/- 0.018 & 0.89 +/- 0.055 g/dl; globulin-0.91 +/- 0.024 & 0.66 +/- 0.015 g/dl). At the end of the stunting phase, significant reduction in respiratory burst, myeloperoxidase and lysozyme activities and significant increase of super oxide dismutase (SOD), catalase (CAT), serum glucose and cortisol were recorded in all groups of stunted fish. However, significant improvement in immunological status of the stunted groups in terms of elevated serum protein (4.33 +/- 0.17 g/dl), globulin (2.10 +/- 0.019 g/dl), respiratory burst activity (1.319 +/- 0.050), myeloperoxidase (0.926 +/- 0.059) and lysozyme activity (64.26 +/- 2.34 U/ml), were recorded in T8 group during post-stunting phase. In contrast, an imbalance in reinstating catalase activity, serum glucose and cortisol levels were evident in fish stunted for a prolonged phase (T12 group), indicating that stunting of milkfish for 8 months can significantly reinstate the physiological recovery in stunted fish which in turn, will prove to be helpful for keeping the fish physiologically healthy during its captive rearing.