How to Tell If Fish Is Bad: Tips & Tricks

by Ella

Fish is a popular and nutritious source of protein, omega-3 fatty acids, and various essential nutrients. However, like all perishable foods, fish can go bad if not stored and handled correctly. Consuming spoiled fish can lead to foodborne illnesses and unpleasant experiences. Therefore, it’s crucial to know how to recognize the signs of spoiled fish to ensure the safety and quality of your seafood dishes. In this comprehensive guide, we will explore the various methods and indicators to determine if fish is no longer fit for consumption.

1. The Importance of Freshness

Freshness is a paramount consideration when working with fish. Unlike many other foods, seafood, including fish, can deteriorate rapidly, affecting both taste and safety. Here’s why freshness is crucial:


Quality and Flavor: Fresh fish has a clean, briny scent and a firm texture. Its natural flavors are at their peak, making it ideal for various culinary preparations.


Nutritional Value: Fresh fish retains its nutritional value, providing essential omega-3 fatty acids, vitamins, and minerals that support overall health.


Safety: Eating spoiled fish can result in foodborne illnesses, including nausea, vomiting, diarrhea, and more severe conditions. Ensuring freshness helps prevent these health risks.


2. The Senses Test

One of the most reliable methods for determining if fish is bad is to use your senses. By closely inspecting the fish, smelling it, and touching it, you can often detect spoilage signs. Here’s how to conduct the senses test:

a. Sight

Visual inspection can provide valuable clues about the freshness of fish:

Color: Fresh fish should have vibrant and consistent coloring. For example, salmon should be a bright pink or orange. Any discoloration, such as grayish or brownish hues, can indicate spoilage.

Texture: Fresh fish should have a smooth and moist surface. It should not appear dry or slimy. A slimy texture often indicates bacterial growth.

Eyes: The eyes of whole fish should be clear, not cloudy. Cloudy or sunken eyes suggest deterioration.

Scales and Skin: Scales should be firmly attached, and the skin should be intact. If scales are falling off or the skin is torn or damaged, the fish might be less fresh.

b. Smell

Your sense of smell is a powerful tool for detecting spoiled fish. Follow these guidelines:

Fresh Odor: Fresh fish should have a clean, ocean-like aroma. It may also have a slightly briny or seaweed scent, depending on the type of fish.

Ammonia Smell: If the fish smells strongly of ammonia or has a pungent, sour odor, it’s likely spoiled and should be discarded.

Fishy Smell: While fish naturally smell like fish, an overwhelming, intensely fishy odor is a sign of spoilage.

c. Touch

Touching the fish can help you assess its freshness:

Firmness: Fresh fish should feel firm and spring back when gently pressed. Avoid fish that feels mushy or leaves an indentation.

Stickiness: Spoiled fish can feel sticky or tacky to the touch due to bacterial growth.

By using your senses to evaluate the fish, you can often make a preliminary determination of its freshness. However, it’s essential to consider additional factors when assessing fish, as individual characteristics can vary.

3. Expiry Dates and Labels

When purchasing fish, especially from a grocery store, pay close attention to labels and expiry dates on the packaging. Understanding these labels can help you select the freshest products. Key information to look for includes:

Sell-By Date: This date indicates when the store should sell the fish. Purchase fish before this date for the best quality.

Use-By Date: This date suggests the last day you should consume the fish for optimal freshness. Consuming the fish shortly after this date is recommended.

Pack Date: Some packages include a pack date, which tells you when the fish was packaged. Fresher is typically better.

Country of Origin: Knowing where the fish comes from can help you make informed choices, as different countries may have varying seafood safety standards.

Sustainability Labels: Look for labels that indicate sustainable fishing practices, such as the Marine Stewardship Council (MSC) certification.

Frozen or Fresh: Determine whether the fish is frozen or fresh. Frozen fish can be an excellent option, as it’s often flash-frozen shortly after catch to preserve freshness.

Refrigeration: Ensure that the fish has been stored properly in the store’s refrigerated or frozen section.

Understanding the information on labels and packaging can empower you to make wise choices when purchasing fish.

4. Handling and Storage

Proper handling and storage are critical to maintaining fish freshness. Whether you’ve just purchased fish or are storing leftovers, follow these guidelines:

a. Purchasing Fresh Fish

Shop Last: If possible, make seafood the last item on your grocery list to minimize the time it spends outside the refrigerator or freezer.

Use a Cooler: If you’re buying fish during warm weather, bring a cooler with ice packs to transport it home safely.

Inspect the Fish Counter: Examine the display case at the store. The fish should be displayed on a bed of ice to keep it cold.

b. Storing Fresh Fish

Temperature: Store fresh fish in the coldest part of your refrigerator at a temperature between 32°F (0°C) and 39°F (4°C).

Airflow: Place fish on a plate or tray and cover it with plastic wrap or aluminum foil to allow for airflow. This prevents condensation and maintains quality.

Use Quickly: Fresh fish is best consumed within one to two days of purchase.

c. Storing Frozen Fish

Temperature: Keep frozen fish at a constant temperature of 0°F (-18°C) or lower.

Airtight Packaging: Ensure the fish is well-sealed in airtight, moisture-proof packaging to prevent freezer burn.

Thawing: Thaw frozen fish in the refrigerator or by using the “defrost” setting on your microwave. Avoid thawing fish at room temperature to prevent bacterial growth.

By handling and storing fish properly, you can extend its freshness and reduce the risk of spoilage.

5. Common Types of Spoilage

Understanding the different types of spoilage that can affect fish can help you identify signs of deterioration. The two primary types of spoilage in fish are bacterial spoilage and enzymatic spoilage.

a. Bacterial Spoilage

Bacterial spoilage is one of the most common causes of fish deterioration. Signs of bacterial spoilage include:

Foul Odor: Spoiled fish often emits a pungent, unpleasant odor, similar to ammonia.

Sliminess: Bacterial growth can make fish feel slimy to the touch.

Discoloration: The flesh may appear discolored, with patches of gray or brown.

Off-Flavors: Spoiled fish can have off-flavors, such as a sour or rancid taste.

b. Enzymatic Spoilage

Enzymatic spoilage occurs due to the action of enzymes naturally present in fish. Signs of enzymatic spoilage include:

Texture Changes: Enzymatic spoilage can lead to changes in the texture of the fish, making it mushy or overly soft.

Off-Flavors: Enzymatic spoilage can also result in off-flavors, such as a bitter or metallic taste.

Both bacterial and enzymatic spoilage can affect the quality and safety of fish, so it’s essential to recognize these signs and avoid consuming spoiled fish.

6. Preventing Spoilage

Prevention is the best approach to maintaining fish freshness. Here are some tips to help prevent fish from spoiling:

a. Buy from Reputable Sources: Purchase fish from reputable suppliers and stores with good hygiene practices and proper refrigeration.

b. Use Proper Storage: Always store fish in the refrigerator or freezer at the recommended temperatures and conditions.

c. Practice FIFO (First In, First Out):  When storing fish in the freezer, use the FIFO method to ensure you use the oldest items first.

d. Avoid Cross-Contamination: Prevent cross-contamination by keeping fish separate from other foods and using separate cutting boards and utensils.

e. Cook Promptly: Cook fish promptly after purchase or thawing to reduce the risk of spoilage.

f. Properly Seal Leftovers: If you have leftover cooked fish, store it in an airtight container in the refrigerator and consume it within a few days.

g. Freeze Excess Fish: If you have more fish than you can consume within a few days, consider freezing it for future use.

7. When in Doubt, Throw It Out

If you have any doubts about the freshness of fish, it’s safer to discard it than to risk foodborne illnesses. Consuming spoiled fish can lead to a range of health issues, and the unpleasant taste and smell are not worth the potential risks.

Additionally, if you notice any signs of spoilage after cooking fish, such as an unusual odor, off-flavors, or changes in texture, it’s best to err on the side of caution and dispose of it.


Recognizing the signs of spoiled fish is a crucial skill for anyone who enjoys seafood. By using your senses, understanding labels, and following proper handling and storage guidelines, you can ensure the freshness and safety of the fish you prepare and consume. Remember that freshness is not only about taste but also about health, making it well worth the effort to become proficient in detecting spoiled fish.



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