Vibrio are bacteria that are mostly found in saltwater and cause serious disease in marine fish. People usually get sick with vibriosis after eating raw or undercooked fish or shellfish or after swallowing contaminated water. Fish affected by Vibrio can have symptoms ranging from deep skin ulcers to more wide-spread signs of skin darkening, scale loss, swelling of the abdomen, and loss of appetite.
In people, Vibrio can cause nausea, vomiting, and diarrhea. Some types of Vibrio can also cause skin infections from contact with contaminated water.
People can prevent vibriosis infections by eating cooked fish and shellfish and by avoiding exposure of open wounds or broken skin to warm salt or brackish water, and avoiding raw shellfish harvested from such waters.
From the Center for Disease Control and Prevention (CDC)