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Eating fish is one of the best ways that you can get some much needed healthy fats and proteins into your diet. 

Beyond that, choosing to eat sustainably sourced fish in lieu of beef or chicken can be better for the environment as well and help to reduce your carbon footprint.

However, when it comes to cooking fish, some people can be at a bit of a loss as to how to prepare it. 

There are a variety of types of fish, and there are a variety of ways to cook those different types of fish. 

In this article, we will discuss one of the simplest ways of preparing your catch (whether you actually caught it or simply bought it): cooking fish in vacuum sealed bags.

Let’s take a look at what types of fish are best prepared this way and go over what you need to know and the equipment you need on hand to make sure that you end up with a perfectly cooked cut of fish every time. 

Different Types of Fish

Before we get into the particulars of vacuum sealing fish, it is important to understand that different varieties of fish will require different methods (and times) for cooking. 

There are oceans full of fish all over the globe and each one of them has different qualities and characteristics.

Not all of the fish in the world’s oceans are safe for consumption, but there are many many different varieties that are safe for humans to eat. 

You could even eat your goldfish if push came to shove. 

If we eliminate shellfish and zoom in to just take a look at the fish that most people around the world have access to, we can separate most fish into “round fish” and “flat fish”. 

This method of separation is literally based on the shape of the fish.

Round fish have a traditionally “fish” shape like salmon or tuna; and flat fish, like flounder or halibut, have flat bodies. 

Insofar as this affects cooking and eating fish, you can generally expect round fish to have two larger filets of meat and flat fish to have four smaller filets that are edible. 

Beyond this initial separation, and more important for the purposes of cooking fish in vacuum sealed bags, is separating fish into lean and fatty fish. 

To ascertain the fat content of different types of fish, look at the color of the meat.

Fish that have white meat or meat lighter in color generally will be leaner, and fish that have darker meat (like sockeye salmon) are usually on the fattier end of the spectrum. 

Low fat fish like cod, halibut, or flounder have more delicate flesh and can easily dry out if they are cooked too long or at too high a temperature. 

Fish on the leaner side generally comes out best when being poached or steamed so that moisture can be maintained in the meat. 

Fattier fish is more conducive to dry-heat methods because the flesh is more capable of holding onto moisture.

Some fattier fish will not taste very good if poached or steamed because these methods encourage their abundant oils to oxidize making the meat taste “off”.

If we take a moment to bring shellfish back into the picture, things like shrimp, crab, and lobster are all on the leaner side of ocean victuals, so they are often best steamed or boiled as well. 

Taking all of this into account, we can derive that it is probably best to cook leaner fish in vacuum seal bags and leave the fattier fish to be pan fried or roasted (though this is not a “hard and fast” rule, and you should always leave a little room for experimentation). 

Vacuum Sealed Fresh Fish vs. Frozen fish

So now that you have a type of fish in mind, there comes the question of “freshness”. 

When it comes to cooking fish in vacuum sealed bags, should the fish be frozen or fresh, or does it really matter at all? 

There is a perhaps misguided yet prevailing notion that fish you buy “fresh” at the supermarket is superior to frozen fish. 

However, this isn’t always the case. Insofar as quality of the fish is concerned, frozen may actually be better.

The fish you see on display in the meat section of most major grocery stores is not guaranteed fresh and was probably previously frozen before being put out in that glass case anyway. 

These days, there are a variety of flash freezing techniques that can preserve the freshness of fish almost immediately after it is harvested. 

Of course there’s good and bad fish on both ends of the fresh/frozen spectrum. 

If you are looking to get fish out of the case, make sure that it isn’t marked as having been previously frozen.

You will be paying more for a product that you can to the frozen foods section and get for much cheaper, albeit with potential added time for thawing out. 

If you buy your fish frozen, make sure that there are not any added chemicals listed on the ingredients panel. 

Some frozen fish can be inundated with chemicals that add bulk to the fish while frozen, but fizzle out when cooked leaving you with a disappointingly small cod filet for Friday night dinner.  

Looking for labels like “frozen fresh” can also be a solid indicator of quality frozen fish.

This insinuates that the fish hasn’t had a chance to lose any of the flavors or nutrients that it came out of the ocean with. 

When you add the idea of cooking fish in vacuum sealed bags to the mix, frozen may win out above fresh. 

Most frozen fish comes already vacuum sealed, so if you’re going straight from the freezer to the pot, it makes sense to leave it as is.

However, you will need to be careful about whether or not the vacuum sealed bag the fish comes in is safe for cooking temperatures. 

If you can not find that information and have doubts, it’s always best to transfer the fish into a cook safe vacuum seal bag, like these FoodVacBags 150 Combo FoodVacBags Vacuum Seal Bags (View at Amazon), before continuing. 

Vacuum sealing fresh fish is also an option. If you fish often, you might be well acquainted with vacuum sealing your own fresh fish. 

Vacuum sealing fresh fish filets with a little bit of seasoning or marinade can be a great way to have multiple easy weeknight dinners.

Just be sure to store the fish that you are not eating right away in the freezer until you are ready for it. 

However, do not ever refreeze fish that has been frozen before as doing so can lead to potential buildups of harmful bacteria on the meat. 

How to Cook Fish in Vacuum Sealed Bags 

Now that you have your fresh or frozen fish sealed up and ready to go, what’s the best way to go about cooking it? 

When cooking anything in a vacuum sealed bag, poaching is the primary method to go to.

Fish in a vacuum sealed bag cannot really conducively be cooked any other way and still come out tasting alright. 

To poach your vacuum sealed fish, you have two options: using an immersion circulator and not. 

Sous vide cooking is characterized by vacuum sealing food and then putting it in a pot of water with an immersion circulator. 

The immersion circulator works to keep the water at a consistent temperature for the entire duration of the food’s time in the pot making for perfectly cooked beef, fish, or what have you everytime. 

We come back to the “every fish is different” concept from before with the concept of sous vide cooking fish.

A denser white fish like halibut will do nicely being vacuum sealed fresh with some butter and seasoning then spending 30 minutes to an hour (always depending on whether your fish is frozen or not and the thickness of your filet) floating in a pot with an immersion circulator after which a quick sear on both sides will have you eating tasty, perfectly textured fish for your next meal. 

If you cook something like cod sous vide, you will not need to do anything but season the fish (preferable but not required) vacuum seal it (if it did not come that way already), and toss it in the pot with the immersion circulator. 

Delicate meat like cod should not be seared after being cooked sous vide for the reason mentioned earlier in the article: the direct heat method of cooking something as delicate as lean white fish tends to dry things out unpleasantly. 

If you do not have an immersion circulator, you can still poach your fish in a vacuum seal bag; you just will not have the same control or precision available with an immersion circulator. 

Make sure to keep an eye on the temperature of your water if you are not relying on an immersion circulator.

You do not want your water boiling when you go to poach fish otherwise you risk it over cooking and turning weird and rubbery. 

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