"Garlic enhances immune functions and has antibacterial, antifungal and antivirus activities. . ." Biological properties of garlic and garlic-derived...[Environ Mol Mutagen. 2009] - PubMed Result And another article regarding garlic's antioxidative properties... Antioxidative and Antigenotoxic Effects of Garlic ...[Plant Foods Hum Nutr. 2009] - PubMed Result Granted, these articles are focusing on the effects garlic has on humans, but it wouldn't be a huge leap to say that garlic probably does beneficiary things for fish as well.