Does tobacco (Nicotiana tabacum) leaf dust save the life of rohu (Labeo rohita) fingerlings during transport?

Abstract

Fishes undergo a multi-phase of stress due to multiple stressors involved during transportation which is an inexorable and indispensable operation in aquaculture. The aim of this study is to promote a novel, inexpensive, active and eco-friendly sedative to replace expensive and toxic sedatives used in aquaculture. With this intention, we investigated the efficacy of tobacco leaf dust as a sedative for the transport of rohu (Labeo rohita) fingerlings. The experiment of sedative efficacy and simulated transportation was conducted for 12 h in glass tanks (30 L capacity) and plastic bags (75 cm length × 45 cm wide), respectively with different concentrations of tobacco leaf dust such as 0 ppm, 25 ppm, 50 ppm, 75 ppm, 100 ppm and 125 ppm among which 0 ppm was used as control. The fingerlings (6.45 ± 0.68 cm and 3.29 ± 0.52 g) were stocked at a stocking density of 10 fishes/ tank and 30 fishes/ plastic bag in triplicates. The induction and recovery times observed in the anesthetic bath significantly (p<0.05) decreased and increased with increase in the concentrations of tobacco leaf dust. The lowest effective dose found to produce induction (≤ 15 min) and recovery (≤ 5 min) was 25 ppm and the same was effective in inducing light sedation in rohu during the behavioral response observation. Mortality rate (15% to 40%) of fingerlings during transportation was significantly higher in control (without sedative) than the sedative doses of tobacco. Also, poor water quality was noticed in control group with the serious changes in hemogram and leukogram of fingerlings. The experimental results revealed the efficacy of tobacco in minimizing the metabolic activity of the fishes and thereby reducing the water quality deterioration and stress during transportation. Therefore, the present study reveals that tobacco leaf dust (25 ppm) could be a futuristic sedative for safe and successful transportation of L. rohita fingerlings.