Effect of packing density on selected tissue biochemical parameters of hatchery produced fingerlings of orange spotted grouper Epinephelus coioides (Hamilton, 1822) during transportaion

Effect of different packing densities on water quality parameters, survival and selected tissue biochemical parameters during transportation of hatchery produced fingerlings of orange spotted grouper Epinephelus coioides (Hamilton, 1822) was investigated. Fingerlings (weight 3.0±0.2 g and length 6.0±0.2 cm) were packed in sealed double layered oxygen packed polythene bags (water and oxygen ratio 1:3) at different packing densities of 20, 30, 40 and 50 no. l-1. The packed fishes were transported for 6 h. After transportation, water samples and tissue samples from fishes were collected for further analyses. Levels of tissue glucose and selected metabolic enzymes (lactate dehydrogenase, LDH; aspartate amino transferase, AST and alanine amino transferase, ALT) significantly (p<0.05) increased with increased packing density. Water quality parameters viz., pH, dissolved oxygen, CO2, alkalinity, total ammonia nitrogen (TAN) and nitrite nitrogen (NO2-N) were also significantly different at higher packing densities (p<0.05). However, levels of all the tissue biochemical parameters tested were in tolerable range and no mortality of fingerlings was recorded at any of the packing densities. Though the tissue enzyme levels were significantly higher and water quality was significantly deteriorated at the highest packing density of 50 no. l-1, it did not lead to mortality of fish. Therefore, it is inferred that this density can be used for short distance transportation of fingerlings of orange spotted grouper.