Aquatic diseases refer to illnesses that affect organisms living in water, including fish, amphibians, and aquatic plants. These diseases can be caused by various pathogens such as bacteria, viruses, fungi, and parasites. Environmental factors like pollution, temperature changes, and habitat destruction can also contribute to the spread and severity of these diseases. In aquatic ecosystems, diseases can have significant impacts on biodiversity and fish populations. For example, ichthyophthirius multifiliis, commonly known as "ich," is a parasitic infection that affects fish, leading to high mortality rates if not treated. Understanding and managing aquatic diseases is crucial for maintaining healthy ecosystems and sustainable fisheries.