How to Ship Seafood: Dry Ice, Packing and Carrier Rules

To ship seafood, freeze or deeply chill it, vacuum-seal it, pack it in a thick insulated foam cooler inside a corrugated box with dry ice (frozen) or gel packs (fresh), and send it by an overnight or next-day service early in the week. If you use dry ice, follow the carrier’s hazmat marking rules: USPS allows up to 5 pounds per package by air, and UPS lets you ship up to 2.5 kg (5.5 lb) by domestic air without a hazardous materials agreement.

Seafood is the least forgiving food you can ship. The cold chain and transit time decide whether it arrives safe to eat, so the packing and service choice matter more than the box itself.

Can you ship seafood through USPS and UPS?

Yes, both carriers accept properly packed seafood within the United States, but neither refrigerates packages. USPS Publication 52 says perishable foods that decompose easily or can’t reach their destination without spoiling are nonmailable, so your packaging has to keep the product safe for the whole trip. USPS recommends Priority Mail Express and Priority Mail for items that need refrigeration, and it says frozen items packed with dry ice ship at the sender’s own risk.

Insurance won’t cover spoilage either. USPS sells insurance for perishable items, but it states that a claim won’t be paid if the item is spoiled, even if it arrived on time. Your real protection is a fast service and enough coolant.

Seafood fits into the wider set of rules covered in our guides to shipping perishable food and shipping frozen food. This guide focuses on what’s specific to fish and shellfish.

Which coolant should you use for frozen, fresh or live seafood?

Match the coolant to the product. Dry ice keeps frozen fish frozen, gel packs keep fresh fish refrigerator-cold, and live shellfish need cool, damp conditions rather than freezing. FDA food-safety guidance puts refrigerator temperature at 40°F or below and freezer temperature at 0°F, which is a sensible target for seafood on arrival.

Don’t use loose wet ice. It melts into water that soaks the box, and USPS requires frozen products to be packed so they don’t leak or cause odors. If you prefer ice, freeze it in sealed bags or use gel packs instead.

What are the USPS dry ice rules for seafood?

USPS allows dry ice in domestic mail only, never international, with different rules for air and ground transportation. The requirements come from Publication 52, Packaging Instruction 9A.

• By air (Priority Mail Express, Priority Mail): up to 5 pounds of dry ice per package. The box needs a Class 9 miscellaneous hazardous material label, the marking “Dry Ice, UN1845” or “Carbon Dioxide Solid, UN1845”, the name of the contents being cooled and the net weight of the dry ice on the address side, plus a Shipper’s Declaration for Dangerous Goods prepared in triplicate and attached to the outside.
• By surface (USPS Ground Advantage): more than 5 pounds is allowed. Mark the box “Surface Only” or “Surface Mail Only” and “Dry Ice, UN1845”. No Class 9 label or shipper’s declaration is needed, but the package must never travel by air.
• Venting: the container must let carbon dioxide gas escape. USPS warns that an airtight container can build pressure until it ruptures, and recommends a thick polystyrene box rather than a thin grocery-store cooler.

In practice, most home shippers sending frozen seafood by USPS use Priority Mail Express with 5 pounds of dry ice or less. Ground Advantage is usually too slow for seafood except over short distances.

What are the UPS dry ice rules for seafood?

UPS rules are simpler for small amounts and for ground shipments within the 48 contiguous states.

• Domestic air, 2.5 kg (5.5 lb) or less: no hazardous materials agreement, no shipping papers and no acceptance audit. Mark the box “Dry Ice” or “Carbon Dioxide, Solid”, describe the contents (for example, “frozen salmon”), and state the dry ice amount or that it is 2.5 kg or less.
• Domestic air, over 2.5 kg: ship through UPS-compliant shipping software, mark “Dry Ice” or “Carbon Dioxide, Solid” with “UN1845” and the weight in kilograms, and expect an acceptance audit and a dry ice accessorial charge listed in the UPS rate guide.
• UPS Ground: dry ice isn’t regulated for ground shipments to and from the 48 contiguous states. Shipments to or from Alaska, Hawaii, Puerto Rico and Avalon, California must go as air shipments.
• International: dry ice may require a UPS International Special Commodities contract.

How do you pack seafood step by step?

1. Chill or freeze first. Frozen product should be frozen solid at 0°F before it goes in the box, and fresh seafood should be as cold as possible without freezing. A cooler only holds temperature. It can’t bring warm fish down.
2. Vacuum-seal and bag. Vacuum-seal portions, then put them in a heavy leakproof liner bag so melt water and fish liquid stay inside.
3. Use a thick foam cooler. Place a thick-walled molded polystyrene cooler inside a snug corrugated outer box. The outer box takes the impacts and the foam holds the cold.
4. Add coolant. Put dry ice on top of frozen product, since cold air sinks, and wrap it in paper so it doesn’t touch the bags directly. For fresh fish, put frozen gel packs around and on top of the product.
5. Fill the gaps. Empty space warms quickly, so fill voids with crumpled paper. Don’t tape the foam lid airtight when using dry ice.
6. Mark and label. Apply the dry ice markings your carrier requires, add “Perishable” and “Keep Refrigerated” (or “Keep Frozen”) on the outside, and put the shipping label on the largest flat surface of the outer box.

Leaks are the most common failure after delays. Our guide to shipping fragile items and valuables covers cushioning and box strength in more detail, which matters for glass jars of caviar or smoked fish.

Which shipping service is fast enough for seafood?

Use an overnight or next-day service for anything fresh or live, and no more than two days for well-packed frozen seafood. Ship Monday through Wednesday so a box never waits in a sorting facility over the weekend.

Overnight service is the costly part of shipping seafood. Compare live UPS and USPS overnight rates for your packed weight in the ParcelPath rate calculator, and count the weight of the cooler and coolant, since they often weigh more than the fish. For the timing differences between carriers, see our guide to overnight shipping options and our Priority Mail Express page.

Can you ship live lobster or shellfish?

Live shellfish fall under carrier live-animal rules, not just food rules, so confirm acceptance with your carrier before you ship. USPS limits mailable live animals to the categories in Publication 52 section 526, and UPS accepts live animals only under its own restrictions and service requirements.

When live shipping is allowed, live lobster and crab need to stay cool, moist and able to breathe. Pack them in damp seaweed or damp newspaper with gel packs in an insulated box, and never submerge them in water or let them freeze. Ship overnight only, for delivery the next morning. Many sellers ship cooked-and-frozen lobster instead, which avoids the live-animal rules and travels with dry ice like any frozen seafood.

What goes wrong when shipping seafood?

• Service too slow. A two-day delay outlasts most coolant. Pick overnight for fresh seafood and ship early in the week.
• Sealed dry ice. An airtight container can rupture. Always leave a path for gas to escape.
• Missing markings. Dry ice without the required UN1845 marking, label or paperwork can be refused or delayed.
• Melt-water leaks. Loose ice soaks the box and gets it pulled from the network. Use gel packs and liner bags.
• Nobody home. Tell the recipient the delivery date so the box goes straight into a freezer.

If you sell seafood, build packaging, coolant and overnight service into your prices from the start. Our guide to product pricing with a shipping calculator shows how to work shipping into your product prices, and the shipping calculator guide explains how carriers price weight, distance and speed.

ParcelPath is free to use, with no subscription, minimums or per-label fees, and gives up to 89% off USPS and up to 85% off UPS retail rates, including the overnight services seafood needs. You can print labels at home, or skip the printer with USPS Label Broker at the Post Office or a UPS Mobile Barcode at The UPS Store. ParcelPath also offers free USPS pickups.

Frequently Asked Questions

How do you ship seafood so it stays frozen?

Freeze the seafood solid at 0°F, vacuum-seal it, and pack it in a thick polystyrene cooler inside a corrugated box with dry ice on top. Fill empty space, keep the container vented rather than airtight, and ship by an overnight or next-day service such as USPS Priority Mail Express or UPS Next Day Air on a Monday through Wednesday.

How much dry ice can you ship with USPS?

USPS allows up to 5 pounds of dry ice per package by air, with a Class 9 label, the marking “Dry Ice, UN1845”, the contents and dry ice net weight on the address side, and a Shipper’s Declaration for Dangerous Goods. More than 5 pounds can go by surface only, marked “Surface Only”. Dry ice is prohibited in international mail.

Does UPS require hazmat paperwork for dry ice seafood?

Not for small amounts. For domestic air packages with 2.5 kg (5.5 lb) of dry ice or less, UPS requires no hazardous materials agreement or shipping papers, only the marking “Dry Ice” or “Carbon Dioxide, Solid”, a description of the seafood, and the dry ice amount. UPS Ground shipments within the 48 contiguous states aren’t regulated for dry ice.

Can you ship fresh seafood with gel packs instead of dry ice?

Yes. Fresh fish and shellfish should stay refrigerator-cold, 40°F or below, not frozen, so frozen gel packs are the right coolant. Surround the vacuum-sealed product with gel packs inside a thick foam cooler, use a leakproof liner bag, and ship overnight. Gel packs aren’t hazardous materials, so no special markings are needed.

Sources

• USPS Publication 52, Packaging Instruction 9A: Dry Ice
• USPS Publication 52, section 349: Miscellaneous Hazardous Materials (Class 9)
• USPS Publication 52, section 53: Fresh Foods and Other Perishables
• USPS Publication 52, section 526: Mailable Live Animals
• USPS FAQ: How do I keep my mailed item cold or refrigerated?
• USPS: Mail and shipping services
• UPS: Shipping with coolants and refrigerants
• FDA: Refrigerator thermometers, cold facts about food safety