Median Lethal Concentration of Zanthoxylumrhetsa seed extracts on Grass carp Fingerlings (Ctenopharyngodon idella) (Valenciennes, 1844) in Captive Condition

Abstract

The bark extracts of the plant Zanthoxylum rhetsahave been widely used by people of ArunachalPradesh as a mean of catching fish. Therefore, themedian lethal concentration (LC50) value of Zan-thoxylum rhetsa bark extracts on grass carp(Ctenopharyngodon idella) (Valenciennes, 1844) hasbeen determined in the present study. The seeds ofZ. rhetsa were collected from the forest of Tarakvillage, located in the Siang district of ArunachalPradesh and the toxicity test was conducted in thecontrol condition. Five different concentrations ofthe extract viz., 25 mg l-1, 35 mg l-1, 45 mg l-1,55 mg l-1 and 65 mg l-1 were prepared by addingthe extracts proportionately to the water. The LC50value of Z. rhetsa against C. idella was hosted as 45mg l-1 for 96 h exposure period. Toxicity of aqueoussolution of Z. rhetsa against fingerlings of grass carpwas found to be time and dose-dependent. It wasfound that there was a significant (p<0.05) relation-ship between the mortality of the treated fish withthe concentration of seed extract of Z. rhetsa. A verystrong correlation coefficient was found between themortality of test fish and exposure of seed extractof Z. rhetsa (r=0.998) at different concentrations. Thefinding established that Z. rhesta has a potentialpiscicidal effect on fish and could be used widelyto control unwanted fishes in aquaculture systems.