For a keto-style meal, start with plain frozen fish and compare the finished product’s carbohydrate figure per 100g with the portion you intend to eat. A butter-finished option may also fit your plan, but check its ingredients and saturated fat: Marks & Spencer lists less than 0.1g carbohydrate per 100g for its wild Icelandic cod, 1.0g for its butter-finished Dover sole and 12.8g for its breaded cod.
Plain fillets give you a straightforward starting point, but the carbohydrate figure for the exact pack and your intended portion still matter. Coatings and sauces can change the finished product’s figures.
A butter-finished fillet may suit the meal you have in mind. Check its carbohydrate and saturated-fat figures alongside ingredients such as milk, rather than judging it by the fish alone.
Use the carbohydrate allowance set for your own plan rather than a generic keto label. University Hospitals Sussex NHS Foundation Trust advises adults with type 1 diabetes to speak to a dietitian before starting a very-low-carbohydrate diet.
Compare the nutrition panel for the whole product first, then consider whether its preparation, portion size and ingredients work for your meal.
| Priority | What to check | Your needs |
|---|---|---|
| Carbohydrate | Read carbohydrate per 100g and calculate it for your portion. Marks & Spencer lists less than 0.1g per 100g for its wild Icelandic cod, versus 6.2g for lightly dusted cod and 12.8g for breaded cod. | I want to know what the fish dish contributes to my carbohydrate allowance, including any coating or sauce. |
| Meal format | Compare the fat and saturated-fat lines as well as carbohydrate. Marks & Spencer lists 1.2g fat per 100g for its cod and hake, while its butter-finished Dover sole lists 10.1g fat and 6.0g saturated fat per 100g. | Would I rather season a plain fillet and choose the rest of the meal myself, or buy fish with a butter-based finish? |
| Portion size | Check the weight you will cook, not just the pack weight. For glazed fish, distinguish the total weight from the stated net fish weight. | One pack may cover several meals; I need a carbohydrate calculation for the portion I will actually eat. |
| Ingredients and handling | Read allergen declarations and instructions for cooking, thawing and refreezing. Butter preparations can contain milk, while dusted or breaded fish can contain wheat ingredients. | I need the finished dish to suit everyone eating it, and I want to follow the storage and cooking directions for that pack. |
The coating can make a substantial difference. Marks & Spencer lists less than 0.1g carbohydrate per 100g for its plain wild Icelandic cod, compared with 6.2g for lightly dusted cod and 12.8g for breaded cod.
Check carbohydrate per 100g and for your portion on the exact pack. Look for flour, starch and breadcrumbs in the ingredients.
Marks & Spencer’s butter-finished Dover sole lists 1.0g carbohydrate and 6.0g saturated fat per 100g, and its ingredients include milk. A low carbohydrate figure does not answer every ingredient or nutrition question.
Compare the full panel with your meal plan and check that the ingredients suit everyone eating it.
Frozen fish can still be raw and require cooking. Fish is an allergen, and prepared products may add milk or wheat ingredients; storage directions can also differ between packs.
Follow the exact pack’s cooking and thawing instructions, including any direction not to refreeze after thawing, and read its allergen declaration.
A brand name cannot establish whether an individual frozen fish product fits your carbohydrate allowance; compare the exact pack and its preparation.
Its frozen-fish range includes plain fillets, butter-finished fish and coated products.
A frozen-fish brand with information about how it freezes its fish and seafood.
Its range includes natural fish fillets as well as prepared fish formats.
Its frozen-fillet listings include wild salmon, hake and Finest cod loins.
Its frozen-fillet listings include salmon, skinless and boneless cod, and basa.
These options cover sliced king fish and pangasius fillets for preparing your own meal. Compare each pack’s carbohydrate figure and the amount of fish you intend to serve.
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King fish slices are an option if you want to prepare and season the fish yourself. Check the carbohydrate figure for your intended portion, and cook the raw fish thoroughly according to the pack instructions.
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The IQF fillets offer portions you can prepare as needed; the named 1kg total weight includes 800g net fish. Use the pack’s carbohydrate figure for the portion you choose, and follow its refrigerator-thawing and no-refreezing instructions.
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This fillet pack is another option for a meal you season yourself. The stated net fish weight is 800g within a 1kg pack; plan portions using the net weight, check carbohydrate for the amount served and follow the pack’s cooking instructions.
Plain fish is a useful starting point when you are keeping carbohydrate intake tightly controlled, but check the exact pack. Marks & Spencer lists less than 0.1g carbohydrate per 100g for its plain wild Icelandic cod, compared with 6.2g for lightly dusted cod and 12.8g for breaded cod.
It can if the finished product’s carbohydrate figure fits your own allowance and its ingredients suit everyone eating it. Marks & Spencer lists 1.0g carbohydrate, 10.1g fat and 6.0g saturated fat per 100g for its butter-finished Dover sole, which contains milk.
No: use the individual plan given by your clinical team rather than a generic product threshold. University Hospitals Sussex NHS Foundation Trust advises adults with type 1 diabetes to speak to a dietitian before starting a very-low-carbohydrate diet.
Follow the instructions on the pack you buy. Marks & Spencer identifies its wild Icelandic cod as raw fish that must be cooked; do not assume a frozen fillet is ready to eat.
Yes. The Food Standards Agency identifies fish as an allergen, and prepared fish can add other ingredients: Marks & Spencer’s butter-finished Dover sole contains milk, while its dusted and breaded cod products contain wheat ingredients. Check the exact pack’s allergen declaration.