* Furunculosis is a bacterial infection caused by the bacterium *Aeromonas salmonicida*. It is one of the most common bacterial diseases of coho salmon and can cause significant losses in aquaculture operations. Furunculosis is characterized by the presence of furuncles, or skin ulcers, on the body of the fish. These ulcers can be small or large and may be accompanied by inflammation and swelling. Furunculosis can also cause internal infections, such as septicemia, which can be fatal.
* Bacterial kidney disease (BKD) is a bacterial infection caused by the bacterium *Renibacterium salmoninarum*. BKD is a chronic disease that can affect coho salmon of all ages. It is characterized by the formation of granulomas, or small lumps, in the kidneys of the fish. These granulomas can interfere with the function of the kidneys and can eventually lead to death.
* Vibriosis is a bacterial infection caused by the bacterium *Vibrio anguillarum*. Vibriosis is a common disease of coho salmon in saltwater environments. It is characterized by the presence of skin lesions, such as ulcers and hemorrhages. Vibriosis can also cause internal infections, such as septicemia.
Viral Diseases
* Infectious hematopoietic necrosis virus (IHNV) is a viral disease that affects coho salmon and other salmonids. IHNV is a highly contagious disease that can cause significant losses in aquaculture operations. IHNV is characterized by the presence of internal hemorrhages and necrosis, or death, of the hematopoietic tissue (the tissue that produces blood cells).
* Viral hemorrhagic septicemia virus (VHSV) is a viral disease that affects coho salmon and other salmonids. VHSV is a highly contagious disease that can cause significant losses in aquaculture operations. VHSV is characterized by the presence of internal hemorrhages and necrosis.
* Infectious pancreatic necrosis virus (IPNV) is a viral disease that affects coho salmon and other salmonids. IPNV is a common disease of coho salmon in freshwater environments. It is characterized by the presence of pancreatic necrosis, or death, and inflammation.
Fungal Diseases
* Saprolegnia is a fungal disease caused by the fungus *Saprolegnia parasitica*. Saprolegnia is a common disease of coho salmon and other salmonids. It is characterized by the presence of white, cottony growths on the body of the fish. Saprolegnia can cause skin infections and can also lead to internal infections.
Parasitic Diseases
* Sea lice are small, parasitic crustaceans that attach themselves to the skin of coho salmon and other fish. Sea lice can cause irritation and inflammation of the skin and can also lead to secondary bacterial infections.
* Leeches are parasitic worms that attach themselves to the skin of coho salmon and other fish. Leeches can suck blood from the fish and can also cause irritation and inflammation of the skin.