How to choose between live fish, fresh fish and frozen fish? Just read this article!

In the wet market, we can always see all kinds of fresh and chilled seafood, and in the supermarket, we can also see pre-packaged fish products that are frozen hard.

Packaged fish usually have corresponding product labels with the source and production date. However, when choosing fresh or chilled aquatic products, we can only see the name and price tag.

Various types of frozen seafood commonly found in supermarkets, most of which contain key information such as origin, scientific name, and production date | PAN1980 Naibeayaus / Wikimedia Commons

How should we choose fish and aquatic products when faced with a wide variety of products? How can we keep the live fish alive for a few more days after we bring it home? Which fish has a lower fishy smell? What kind of fish is Basa fish? For all kinds of questions about buying fish, just read this article!

How the fish gets to market

First, we need to see if the fish is farmed or wild caught.

Farmed fish come from various farms or breeding bases. After being caught and loaded onto trucks, they are transported to wholesale or shipping centers in various regions by logistics. This transportation process may be limited to the city or between nearby cities, or it may cross the north and south of China and cover thousands of kilometers.

Once at the distribution center, the fish will be bought by buyers and further transferred to the secondary wholesale market, where they will be handled by several rounds of middlemen, or directly imported into the market or supermarket. Many fishmongers in wet markets purchase their fish from wholesale markets. If the quantity is very small, the fish farmers may also connect with the market themselves and sell it in wet markets.

If it is wild-caught aquatic products, there are usually people responsible for purchasing them at the dock. After that, they will be sold to secondary dealers or sold by themselves. After layers of transportation and transfer, they eventually become the fish that everyone sees in supermarkets or vegetable markets. At the same time, the price of fish is also invisibly increased layer by layer, becoming the market price we see.

The first-hand price is indeed the most affordable, but the purchase quantity is also very high - the larger the quantity, the cheaper it is. For ordinary consumers like us who occasionally eat fish at home, it is better to buy it in supermarkets or vegetable markets!

The common supply chain process of fish, from catching to processing, transportation, retailers and finally reaching ordinary consumers, the process is complicated | ZCOOL

Sharp eyes to identify good fish

How to choose a fresh frozen fish in the market?

A widely used method is to see if the fish gills are red. However, some unscrupulous vendors may use carbon monoxide to keep the fish gills bright red. For frozen fish, simply looking at the fish gills may not be reliable.

Tips for buying fresh frozen fish

By combining pressing, smelling and observing, we can select the freshest fish possible:

"Press" refers to pressing the fish's body. If the collapse recovers quickly after releasing it, it means the fish is fresh; if the collapse recovers very slowly or does not recover at all, it means the fish is no longer fresh.

"Smell" means smelling the gills of the fish. If it is a fresh fish, we should smell a sea smell or a slight fishy smell, not a medicine smell or other strange smell.

"Cha" means to look. We can see whether the fish's scales are shiny, whether its eyes are bright and clear; if the fish is held horizontally, will its body remain horizontal or will it bend and droop. If the scales are shiny, the eyes are not cloudy, and the fish's body can basically remain horizontal when held horizontally, if these three standards are met, then the fish is very fresh and is suitable for buying home to make a good meal.

If you think the combination of the above steps is too troublesome, we can choose one or two steps, among which "smell" or "hold horizontally" are the most reliable.

These criteria are based on the changes in the fish's body after death. In fish that have died recently, myosin has not been completely broken down and the muscles are still elastic. After death, fish will experience a period of rigor mortis, during which the body can remain horizontal. As time passes, the body becomes softer and will bend and droop when held horizontally. The luster of the fish's scales and eyes also depends on the degree of death of the fish and the corruption caused by microbial infection.

After a fish dies, it will go through the pre-rigor mortis, rigor mortis, and post-rigor mortis. The left side shows the gradual changes in the fish's body after death, and the right side shows the morphology of muscle fibers. The longer the time after death, the more dispersed the muscle fibers are | Liu Shi et al.

If it is a live fish, how should we choose it?

Tips for buying live fish

Observe the fish to see if there are any injuries on its body, if the mucus has fallen off, if the eyeballs are covered with white, and if its swimming posture is normal;

Check the water used to raise fish to see if the water is normal, colorless and transparent, or has a yellow or slightly green tint;

Smell the fish and check if there is any peculiar smell.

It is important to note that if the water color is abnormal or the fish smells strange, then the fish may have been treated with chemicals.

If it is frozen fish, it is more difficult to identify. They are likely to be cut into pieces rather than whole fish, and most of them have been packaged and frozen hard, which increases the difficulty of identification.

In this case, we can look at the production date and choose fresher ones. If it is a whole frozen fish, we can observe whether the fish is damaged or not. For frozen fish cut into pieces, we can observe whether the cut surface of the fish is neat, whether there are small pieces of thawed frozen on the edge, whether the meat is dry, whether the color is natural, whether the ice is evenly wrapped, etc., to judge whether the frozen fish is fresh. Buying frozen fish products from branded merchants is relatively more reliable.

Frequently asked questions when buying fish

How do fishmongers keep live fish alive longer? I bought live fish, how can I keep it alive for a few more days?

Let's not talk about the abnormal way of drugging for now. Good water quality and sufficient oxygen are the tricks of the merchants to keep the fish alive longer. If you buy live fish, you can try to ask the fishmonger for more fish water to take home and keep it for a few more days at home. If the fish is dying on your way home, it is not recommended to try to keep it alive, just put it in the pot!

Is frozen fish not as good as live fish and chilled fish?

We often see frozen fish that have been frozen (-15 to -20 degrees Celsius) and lack effective packaging. The taste of this kind of fish will be slightly worse, and the nutritional value will gradually lose over time. However, if the frozen fish is handled and stored properly, it may not be inferior to live fish and iced fish.

The tuna sashimi we eat is actually frozen fish, but the taste is often as good as fresh fish - this is all due to ultra-low temperature freezing technology. The staff will kill the live fish in an appropriate way, remove substances that may cause corruption or odor (blood, gills, etc.), and then use ultra-low temperatures of -55 to -65 degrees Celsius to quickly freeze it, so as to avoid the formation of ice crystals during the freezing process and prevent damage to fish cells. Moreover, ultra-low temperatures can significantly reduce the speed of various chemical reactions and slow down the proliferation of microorganisms. In this way, even if the tuna is transported over long distances, its nutritional value and deliciousness will not be affected at all.

Tuna frozen with ultra-low temperature technology can be stored at ultra-low temperature for 2 years and still remain highly fresh | Wikimedia Commons

Can the live fish and chilled fish purchased be frozen and stored for a long time?

Live or freshly chilled fish can be kept in the refrigerator for up to about 1 year, but some preparatory steps are required:

Choose a fish that is fresh enough;

Remove the internal organs and blood, which are prone to corruption;

The fish no longer touches water, retains its original appearance, and is directly bagged and vacuum sealed.

Among these steps, vacuum sealing is the key. Vacuum can prevent the fish from contacting air, minimize the activity of microorganisms, and help lock in moisture and preserve the taste of the ingredients. If vacuum sealing is not achieved, the shelf life of the fish will be greatly reduced to only a few months.

Why is Basa fish so cheap? Is it unsafe?

Basa fish is cheap because of its large breeding volume, low breeding cost and high meat yield. Although my country also breeds a small amount of Basa fish, it is mainly imported in large quantities from Vietnam and other places to meet the consumption needs of the Chinese people. Although Basa fish itself is resistant to low oxygen and has strong adaptability, the Basa fish we eat are generally aquatic products that are legally and regulated, and are not grown in stinky ditches. You can eat it with confidence!

However, basa fish is sometimes used to impersonate sole because its fillet looks similar to sole fillet. Basa fish generally refers to giant catfish, while sole refers to flatfish, and the price of the two fish differs several times.

Where does fish smell fishy? Which fish has less fishy smell?

The fishy smell of fish generally refers to the earthy smell, which is more common in freshwater fish. However, the earthy smell of fish has nothing to do with the type of fish, but is related to their living environment.

If the fish's growth environment contains more humus, which is suitable for microbial reproduction, the blue algae, green algae and actinomycetes attached to the water will release earthy smell substances into the water, including geosmin and 2-methylisoboneol. After being ingested by fish, these substances are distributed in the fish's body and become the earthy smell we taste. If animals such as chickens and cows drink water containing earthy smell substances, their meat will also have a fishy smell.

For fish that tend to have an earthy smell, removing the black film during processing is the key, because it is rich in some fat-soluble substances, including earthy smell substances.

When handling fish that are prone to carrying earthy smells, it is best to remove this black film | kknews

The fish has already been killed, why is it still jumping on the chopping board?

The spinal cord of a newly dead fish is generally not damaged and still maintains a certain degree of activity. Muscle movement is controlled by the spinal nerves, and the nerve cells are not damaged. Although the fish is dead, the muscle tissue of the fish can still respond to stimulation, usually with throbbing spasms.

Many of the cooked fish on TikTok were still jumping because of this reason | The Sun / YouTube

Author: Seafood Knowledge

Edit: Cat Tun

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