Acute lethal toxicity of dried garlic (Allium sativum) powder on orange-spotted grouper (Epinephelus coioides) juveniles under static exposure

Abstract

The present study was carried out to assess the toxic effect and determine the lethal concentration of dried garlic (Allium sativum) powder on the orange-spotted grouper (Epinephelus coioides) juveniles. Laboratory static bioassays were conducted to determine the 96-h LC50 of different concentrations of garlic (0, 30, 60, 90, 120, 150 and 180 mg L-1) on grouper juveniles (mean weight, 35.4±6.18 g and mean length, 13.2±0.51 cm). The 96-h LC50 was 74.78 mg L-1 with lower and upper confidence limits of 62.8 and 89.06 mg L-1, respectively. All fish exposed to 30 to 180 mg L-1 exhibited rapid movement, faster opercular activity and erratic swimming whereas at higher concentrations (90 mg L-1 to 180 mg L-1) fish showed additional behavioral changes such as loss of balance, lethargy, gulping for air and respiratory distress. Water quality parameters were within the recommended acceptable limits. This LC50 value can be used as a baseline reference to generate an effective concentration of garlic for future prophylaxis and treatment for parasitic, viral and bacterial infection in grouper.