Aquasonic Bactonex is a preventative treatment formulated to protect freshwater and marine fish against bacterial, fungal, and protozoal external infections, such as velvet, white spot, chilodonella, Trichodina, and Trichodinella. It is used especially during water changes, when adding new fish, or in quarantine systems to preempt outbreaks. The product is not safe for corals or invertebrates and filtration carbon should be removed when treating. The usual dosage is 10 mL per 40 L of aquarium water, with a repeat treatment after about 5 days if needed. The active ingredients include aminacrine hydrochloride and methylene blue.