Effects of Alpinia galanga oil on anesthesia and stress reduction in Oreochromis niloticus

Abstract

Oreochromis niloticus (Nile tilapia) is one widely cultured fish in Thailand. Handling processes and transportation causes high stress in Nile tilapia. This study explores anesthetic effect and stress reduction of Alpinia galanga oil (AGO) on Nile tilapia. The anesthetic activity was evaluated by the time for fish induction to anesthesia and full recovery. It was found that the suitable dose of AGO that caused desirable anesthesia of Nile tilapia was 700 mg/L. This dose gave induction and recovery times of approximately 257 and 438 sec, respectively. Blood glucose and plasma cortisol of the fish anesthetized with AGO showed nearly normal levels indicating that the fish stress during handling was not increased. Study on loading densities of fish mimicked general fish transportation and showed that loading density of fish was a crucial factor on fish stress. The highest water quality was found in the lowest loading density of fish. Water containing AGO at a concentration of 150 mg/L showed significantly higher potential for reducing fish activity and water improvement than without AGO. Therefore, AGO is a promising natural edible plant oil for anesthesia in Nile tilapia.