When your finned friends have fungal infections， give them the treatment they need to get healthy. Fritz Expel-F Fish Treatment is a fast-acting， effective and aquarium safe formula designed to treat harmful， true fungal infections such as fin rot， Ichthyophonus hoferi and Saprolegnia. The fast dissolving powder is suitable for both freshwater and saltwater aquariums and treats with just one dose. Treatment period is 14 days. It is safe for most plants and invertebrates—however it will negatively impact Bryopsis algae growth. For best results， use treatment powder in a quarantine tank.