Ichthyophthirius multifiliis, commonly known as "ich," is a parasitic protozoan that infects freshwater fish. It is a major concern for aquarium and pond owners as it can cause significant health problems and even death in fish populations. How Ichthyophthirius multifiliis Infects Fish Ichthyophthirius multifiliis infects fish through the following steps: Tomite Release: When a cyst