Fritz Expel-F is safe and effective anti-fungal medication for treating infections such as Ichthyophonus hoferi and Saprolegnia, as well as certain other true fungal infections. Fungal infections are generally characterized by white, patchy, cotton-like growths on the body, mouth, or fins. Fungal infections usually occur as secondary infections from a previous wound or injury. Without treatment, fungal infections will spread and ultimately cause death. Fritz Expel-F will negatively affect Bryopsis algae growth. If a treatment for preventing or treating fungus on fish eggs is needed try Maracyn Oxy. Fast Treatment for True Fungal Infections. Easy Packet Dosing System. Can Be Used with Other Meds. Safe for Most Invertebrates and Plants. Safe for Fresh and Saltwater Systems.