If you eat fish that smells bad, the smell indicates that the fish is not likely to taste good. In general, that fishy smell also indicates that eating that fish may lead to gastrointestinal problems later.

The Food and Drug Administration (FDA) has established special regulations for certain types of marine fish. Some types of ocean fish that haven't been processed or handled properly can develop toxins called scombrotoxin, which when eaten at high levels, can cause humans to become ill.

Symptoms of scombroid poisoning can start within minutes of eating tainted fish and can include dizziness, nausea and symptoms that resemble an allergic reaction. At the severe end, scombroid poisoning can make it hard to breathe and cause blurred vision. The symptoms of scombroid poisoning can last for up to two days.

Fish that can develop scombrotoxin include:

• Mahi-mahi
• Tuna
• Mackerel
• Anchovies
• Sardines

The FDA regulates how all fish are handled from the moment they are caught until they are purchased by a consumer. Not only does knowing this kind of information help you ask questions about the proper handling of these kinds of fish before purchasing them, but it will help you decide whether it is safe to eat these fish when fresh caught. If your local fishmonger gives you some fish that hasn't been kept properly cooled, that fresh fish may make you sick.