Name one common parasitic infection found in marine fish.

One common parasitic infection found in marine fish is Ichthyophthirius, also known as "ich" or white spot disease. This protozoan parasite is particularly prevalent in freshwater environments but can also affect marine fish, especially under conditions of stress. Ichthyophthirius affects fish by invading their skin and gills, leading to significant irritation and secondary infections if not treated.

Mycobacteriosis, while a serious condition affecting fish, is actually bacterial rather than parasitic in nature. Similarly, fungal infections can occur in fish but are not classified as parasites. Viral hemorrhagic septicemia is a viral infection, which, again, is different from a parasitic infection. Understanding the specific classification of pathogens affecting marine fish, such as recognizing the differences between parasitic, bacterial, fungal, and viral infections, is crucial for accurate diagnosis and treatment.