1. Spoilage Indicators

• Odor: A strong, unpleasant smell is a primary indicator that fish has spoiled. Fresh fish should have a clean, oceanic aroma, while a pungent or sour smell suggests bacterial growth and potential spoilage.
• Texture: Fresh fish should feel firm. If the fish is slimy or mushy, it is likely spoiled. A slimy coating is a clear sign of deterioration.
• Appearance: Fresh fish should appear vibrant and shiny. Dull hues, especially in the flesh, indicate spoilage.
• Eyes: Clear, bulging eyes are a sign of freshness. Cloudy or sunken eyes suggest the fish is past its prime.

2. Health Risks

• Foodborne Illnesses: Consuming spoiled fish can lead to foodborne illnesses, which may cause symptoms such as nausea, vomiting, and abdominal pain.
• Toxins: Some fish can contain harmful biotoxins, even if they appear fresh. For example, certain species like barracuda and moray eel can cause ciguatera fish poisoning, which is not eliminated by cooking.
• Scombroid Poisoning: This occurs when fish that have high levels of histamine due to improper storage are consumed. Symptoms can include rash, headache, and gastrointestinal distress.
• Tetrodotoxin: Found in pufferfish, this toxin can be fatal and is not destroyed by cooking. Symptoms include numbness, difficulty breathing, and potentially death.

3. Specific Cases of Stinky Fish

• Sour Herring: This Swedish fermented herring is known for its extremely strong odour. While it is a traditional delicacy, it can pose risks if not prepared correctly. The fermentation process can lead to the production of gases that may cause cans to explode if not handled properly.
• Canned Fish: Improperly canned fish can lead to botulism, a serious illness caused by toxins produced by Clostridium botulinum bacteria. Signs of spoilage in canned fish include bulging cans and foul odours.

4. Safe Practices

• Storage: Always store fish at appropriate temperatures (below 41°F for refrigeration and 0°F for freezing) to inhibit bacterial growth.
• Inspection: Before consuming fish, inspect its smell, texture, and appearance. When in doubt, it’s safer to discard questionable fish.

Cooking: While cooking can kill some bacteria, it may not eliminate all toxins produced by spoiled fish. If fish smells bad before or after cooking, it’s best not to consume it.