Simulated transport of silver therapon (Leiopotherapon plumbeus) fingerlings at different durations and loading densities: Effects on survival and water quality

Abstract

The silver therapon, Leiopotherapon plumbeus, is being promoted as a new species for aquaculture. However, information on the optimal conditions for the transport of this species for grow-out culture needs to be established to avoid stress and unnecessary mortalities. This study examined the effects of duration of transport and loading density on survival and water quality during simulated transport of silver therapon (Leiopotherapon plumbeus). Hatchery-produced fingerlings [1.30±0.34 g body weight (BW); 44.30±3.77 mm total length (TL)] were held in double-layered oxygenated plastic bags at three transport durations (6 h, 9 h, and 12 h) and densities (40 fish bag^-1, 80 fish bag^-1, and 120 fish bag^-1) in triplicates. Mean survival rates were not significantly affected by both duration of transport (P=0.321) and loading density (P=0.345). However, a highly significant effect of duration of transport on dissolved oxygen (DO) and pH (P=0.000), and a significant effect on Total Ammonia Nitrogen (TAN; P=0.039) and total bacterial count (TBC; P=0.034) were evident. Similarly, water quality parameters were significantly influenced by loading density (P=0.000), with lower DO and pH levels, and higher TAN and TBC recorded at 120 fish bag^-1 density. Since a very high survival rate (>99%) is achieved at the highest loading density of 120 fish bag^-1 up to 12 h transport, this density can be recommended to transport silver therapon fingerlings. However, chemical treatments using either salt, methylene blue, or tropical almond leaf extract in transport water may be used to reduce the high bacterial count during transport.