Behavior changes and \(\mathsf{LC_{50}}\) of dried garlic (Allium sativum) acute toxicity in Nile tilapia (Oreochromis niloticus) juvenile

Abstract

Plant-based compounds are emerging substitutes for chemical treatments in aquaculture since they are known to cause less harm to both the environment and its organisms. Garlic (<em>Allium sativum</em>) is a popular herb that has a broad range of uses, especially in the control and treatment of bacterial and parasitic diseases. However, its toxicity to tilapia is not well-studied. Hence, this study was conducted to test the toxicity levels of garlic powder in juvenile Nile tilapia (<em>Oreochromis niloticus</em>) by determining the cumulative mortality and median lethal concentration (LC₅₀). Test fish were exposed through immersion in 6 concentrations (150, 200, 250, 300, 350, and 400 mg L^-1) of garlic powder with 25% allicin and a control in 96 h static bioassay. Within 24 h, test fish exposed to 250 mg L^-1 garlic and above, exhibited abnormal behaviors such as lethargy, gasping for air, and weak responses to environmental stimuli. Cumulative mortality was highest at 100% in 400 mg L^-1 garlic at 48 h. Mortalities were dependent on the concentration and duration of exposure. The 96 h LC₅₀ of garlic powder to <em>O. niloticus</em> is 225.86 mg L^-1 with lower and upper confidence limits of 210.37 and 242.50 mg L^-1, respectively at 27°C.