Garlic is a safe and healthy vegetable that can be given to your aquarium fish by cutting it into small pieces, using garlic powder, or adding garlic water to the fish tank. Garlic is anti-viral, anti-fungal, and anti-bacterial, which can treat and cure sick fish. It increases the appetite of fish and makes the food more palatable for them. Garlic also boosts the immunity and antioxidant activity of fish. It contains allicin, a compound that has antimicrobial and antiviral properties. Garlic promotes growth and decreases mortality in fish.