Start with the package label, then thaw fish in the refrigerator or use a quick method allowed by the label and local guidance. The U.S. FDA seafood guide recommends refrigerator thawing; for faster thawing, it allows a sealed plastic bag in cold water or microwave defrost only when you will cook the fish immediately. The University of Maine Cooperative Extension advises removing frozen fish from vacuum-sealed packaging before letting it thaw. Packaging directions can differ, so read them and ask the seller or manufacturer if unclear.

Thaw and handle it safely

  • 1. Check for vacuum or reduced-oxygen packaging and read the thaw instructions. Remove the fish from its original vacuum package while still frozen, before any thawing. For cold-water thawing, transfer it to a new leakproof bag. Do not leave vacuum-packed fish at room temperature or invent a fixed thawing window.
  • 2. When time allows, thaw in the refrigerator. For a quick method, seal the fish against leaks and immerse it in cold water; if you use a microwave, cook it immediately afterward as FDA advises. Do not thaw on the counter or in warm water.
  • 3. Keep raw fish separate from ready-to-eat food and use a dedicated board and knife when possible. Wash hands, tools and surfaces before handling cooked food or produce.
  • 4. Check the thickest part with a food thermometer. FDA guidance says most seafood should reach 145°F (63°C). Follow local official guidance and the package where you live.

A hypothetical dinner plan

Suppose you plan to cook a frozen vacuum-packed fillet for dinner. Read its label first; remove the fish from its original vacuum bag while still frozen; for cold-water thawing, transfer it to a new leakproof bag. Thaw in the refrigerator, prepare it on a raw-fish board, then wash the work surface. Measure the thickest portion and cook to the applicable local safety guidance. The package size and refrigerator temperature determine timing, so this example does not promise a thaw duration.

Limits and jurisdiction

Fish species, package type, thickness, refrigerator temperature, and cooking method vary. Do not apply fixed claims such as “12–24 hours,” “3°C,” or “21°C water” to every product. The Maine Extension vacuum-pack note is a specific packaging precaution, not a universal thaw-time chart. Follow the label and local food-safety authority.