Garlic extract to treat fish infections? A research team first assesses the effects of garlic on tilapia

Garlic works with tilapia not only as a culinary ingredient, but also as a treatment for fish health problems in the farm. Garlic contains active compounds such as allicin that have antimicrobial and antiparasitic properties in fish, making it a potential organic and environmentally safe remedy over chemical treatments.

However, too much garlic in the water can also be toxic to fish. Thus, a research team at SEAFDEC/AQD, led by Associate Researcher Gregoria Erazo-Pagador conducted a study to examine the toxicity of garlic powder on Nile tilapia.

With her assistants, Haydee Dumaran-Paciente and Blan Jericho Caloyloy, Ms. Pagador immersed juvenile Nile tilapia in different concentrations of garlic powder, from 150–400 milligrams per liter, and compared their responses and mortality rates to a control treatment with no garlic powder. They then computed for the 96-hour median lethal concentration of garlic powder which is the concentration where half of the exposed fish will die in a span of 96 hours.

The findings revealed that exposure to higher concentrations of garlic powder, specifically 250 milligrams per liter and above, resulted in abnormal behaviors like lethargy and gasping for air. The mortality rate was also significantly higher at a concentration of 400 milligrams per liter.

Based on the findings of the study, the researchers established the median lethal concentration of garlic powder for Nile tilapia to be 225.86 mg per liter at a water temperature of 27 °C. These findings emphasize the importance of understanding the potential impacts of natural compounds like garlic on aquatic organisms before considering them as alternatives to chemical treatments in aquaculture practices.

The research team published the results of their study in the research note, “Behavior Changes and LC₅₀ of Dried Garlic (Allium sativum) Acute Toxicity in Nile Tilapia (Oreochromis niloticus) Juvenile” in Volume 106 Issue No. 2 of the Philippine Agricultural Scientist. You may request for a copy of their publication here: https://repository.seafdec.org.ph/handle/10862/6448