How to Freeze Fresh Fish Properly (and How Long It Keeps)

TL;DR: Freeze it the day you buy it, dry it, portion it, wrap it so no air touches the flesh, freeze it flat at minus 18°C, and thaw it overnight in the fridge. Lean white fish keeps six months, oily fish three.

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Most people who say they do not like frozen fish have only ever eaten badly frozen fish. Fish is 70 to 80 percent water, and freezing water inside a delicate muscle structure is where the whole thing can go wrong. Get it right and a fillet you freeze in August is very good in November. Get it wrong and it comes out dry, cottony and grey.

The good news is that all of the technique is in the first fifteen minutes.

Why fish suffers in a home freezer

Two things damage frozen fish.

Ice crystals. Water inside the flesh expands as it freezes and punctures the cell walls. Slow freezing makes big crystals and lots of damage. Fast freezing makes small ones. This is why commercial fish frozen at sea at minus 40°C often beats what you can do at home, and why you want your fish flat and in the coldest part of the freezer rather than stacked in a warm door shelf.

Air. Any air touching the surface pulls moisture out of it over time, which is freezer burn. The dry white patches are not dangerous but that flesh is finished. Airtight wrapping solves this completely.

The method

1. Freeze it early, not late. The most common mistake is buying fish on Saturday, leaving it in the fridge until Tuesday and then freezing what is left. You have frozen four day old fish. Decide on the day you buy: cooking within 24 hours, or into the freezer.

2. Rinse and dry. A quick cold rinse, then pat it properly dry with paper towel. Water sitting on the surface turns straight into crystals.

3. Portion it now. Split it into the amounts you actually cook, two fillets, four fillets, 500 grams of prawns. A single frozen block means thawing all of it to use any of it, and every refreeze costs quality.

4. Wrap it airtight. In order of effectiveness:

• Vacuum sealer. The best result by a clear margin. Worth owning if you buy seafood regularly.
• Cling film plus a freezer bag. Wrap each portion tightly in film, press out every bubble, then seal in a bag with the air squeezed out.
• The water displacement trick. Put the portion in a zip bag, lower it into a bowl of water so the water pressure pushes the air out, then seal it just above the water line. Nearly as good as a vacuum sealer and free.

5. Label it. Fish type and date, in marker on the bag. Three months from now, a frosted bag of white fillets could be anything.

6. Freeze flat. Lay the packets flat on a tray in the coldest part of the freezer, not in the door. Once solid you can stack them upright like files, which also makes the freezer usable.

How long different seafood keeps

At minus 18°C or colder, airtight:

• Lean white fish (snapper, barramundi, ling, flathead, whiting, coral trout): about 6 months.
• Oily fish (salmon, ocean trout, tuna, mackerel, sardines): about 3 months.
• Green prawns: 3 to 6 months.
• Cooked prawns: 2 months, and they are never quite the same, so cooked prawns are better eaten fresh.
• Squid and octopus: 3 to 4 months. Both actually benefit from freezing, because the ice damage helps tenderise them.
• Mussels, oysters and other live shellfish: do not freeze them live. Cook first, freeze the meat, use within 2 months.
• Whole fish, gutted: 4 to 6 months if wrapped well, though portions are easier to manage.

Oily fish has the shorter life because its fats oxidise slowly even at freezer temperatures. It never becomes unsafe, but past three months salmon starts to taste faintly of old oil.

These are quality windows, not safety deadlines. Fish frozen solid stays safe indefinitely. It just stops being worth eating.

Freezing a whole fish

If you have a whole fish and no room to fillet it first:

1. Scale and gut it. Guts are the fastest route to off flavours.
2. Rinse the cavity thoroughly and dry it.
3. Wrap tightly in cling film, then in foil, then into a bag.

The old trick of glazing works well for whole fish. Freeze the fish bare for an hour, dip it briefly in ice water so a thin shell of ice forms over it, then return it to the freezer. Repeat twice. That ice shell is a perfect airtight barrier and it is what commercial operations do.

Thawing, which matters as much as freezing

You can undo good freezing in an hour of bad thawing.

• Best: overnight in the fridge on a plate, still wrapped. Around 12 hours for fillets.
• Faster: sealed in a bag, submerged in cold water, 30 to 60 minutes. Change the water once.
• Never: on the kitchen bench, in hot water, or in the microwave. The outside warms into the bacterial danger zone while the middle is still frozen, and the texture goes with it.

Once thawed, cook within 24 hours. Pat it dry before it hits the pan, because thawed fish releases water and wet fish steams instead of searing.

You can cook some things straight from frozen. Thin fillets, prawns going into a curry and squid rings for a stir fry are all fine from solid. Add a few minutes and expect a little extra liquid in the pan.

Signs the freezer has beaten you

• White, dry, papery patches: freezer burn. Cut those bits away, the rest is fine.
• A yellow tinge on salmon or tuna: the fats have oxidised. Edible, but it will taste of it.
• Thick frost inside the bag: the package was not airtight, or the freezer has been opened and closed a lot. Use it soon.
• A sour or ammonia smell once thawed: that fish was not fresh before it went in. Bin it.

Quantity Planning

Freeze in the portions you cook, not the portions you bought.

Fish fillet, main course: 180 to 220 grams per adult, so bag two fillets for a couple and four for a family. Green prawns for a curry or pasta: 500 grams feeds four as part of a dish. Squid for a stir fry: 400 grams for four.

Where to Source It

Tasman Star runs fresh fillets, whole fish and green prawns through the counter daily, plus a frozen range including lobster tails and prawns that were snap frozen far colder than any home freezer can reach. If you are buying to freeze, tell the team and they will portion and bag it for you at the counter, which saves you the messy part.

Find us at 5 to 7 Olsen Ave, Labrador or 20 Casua Dr, Varsity Lakes, open 7 AM to 6 PM, 7 days.

Browse fresh and frozen seafood and order online for Gold Coast delivery.