Eating contaminated fish can have serious health effects, such as inflammation, nerve damage, cancer, and more. Some of the symptoms of fish poisoning include nausea, vomiting, diarrhea, abdominal pain, headache, dizziness, numbness, tingling, weakness, and difficulty breathing. Some of the diseases that can be caused by eating contaminated fish include mercury poisoning, lead poisoning, arsenic poisoning, PCB poisoning, dioxin poisoning, and radiation sickness.