How To Ship Fish Safely: Domestic and International Shipping

Fish In A Plastic Bag With Water
Fish In A Plastic Bag With Water
Dr. Mollie Newton
Published by Dr. Mollie Newton PHD| Senior Editor
Last updated: May 8, 2024
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Shifting fish during a journey is considerably more intricate than moving with other pets owing to the significant planning and work involved. It’s not just about selecting suitable packaging and transportation methods to assure the secure delivery of your fish to their new destination, but also entails prepping your fish for the extended trip ahead.

Article Summary

  • Factors affecting the safety of shipped fish include fish species, travel time, temperature and weather conditions, movement and handling during transit, ammonia and carbon dioxide levels, and oxygen supply.
  • Selecting a delivery option with tracking can provide peace of mind and help monitor the fish’s journey.
  • It’s important to educate the recipient on how to acclimate the fish properly upon arrival.

Over the years as an aquarist, I’ve had to transport fish countless times, both when I’ve moved house and sold fish to other hobbyists.

It’s always a nerve-racking task, but I’ve never experienced any fatalities with the fish I’ve sent out – they’ve all arrived happy and healthy.

Whether you’re sending fish to a new owner or moving house and need some advice on how to securely transport aquatic animals, I’ll be sharing my tips and tricks on how to ship fish the right way.

Can You Ship Live Fish?

Fish in Plastic Bags
Fish in Plastic Bags

Yes, you can ship live fish! Most postal service outlets across the world will accept live aquatic animals as long as you follow their packaging and labeling guidelines, which you will be able to find on the delivery service’s official website.

Pet stores and aquarium retailers that sell fish normally receive their stock via delivery trucks or post, so shipping live animals or fish is actually a very common occurrence.

Is It Safe for Fish to Be Shipped?

There are always going to be risks when shipping fish, but provided the package is safe, secure, and is not in transit for an extended period of time, survival rates tend to be pretty high.

Some fish ship better than others – delicate or sensitive species can be challenging as the process of being shipped can be very stressful.

Additionally, other factors like the health of the animal, weather conditions, and how the package is handled during shipment will all influence the survival of the fish when it arrives at its destination.


If you’re purchasing fish online, make sure you’re buying from a high-quality and respected seller to decrease your chances of receiving sickly or dead fish. Nobody would want to deal with the disposal of a dead fish after it has been delivered.

How to Ship Live Fish

Selling fish can be a great way to earn some extra money or even turn into a successful business, but you’ll need to learn how to properly ship aquatic animals, otherwise, you run the risk of your fish dying during transit (and consequently, unhappy customers!).

To transport fish safely, you’ll need to select the right packaging (sturdy outer corrugated box, insulated inner box, fish transport bags, heat/cool pads, insulating material, etc), quickest delivery option, and avoid sending out aquatic life during adverse weather conditions.

Below are the things you need to consider to ensure the safety of your fish while they are being transported to their new home.

Things to Consider

Man in a Blue Shirt Preparing to Transport Fish
(1) Man In A Blue Shirt Preparing to Transport Fish

Fish Species

You need to consider what kind of fish you’ll be shipping. Some fish breeds might need extra precautions to ensure their safety or the safety of other fish.

For example, when shipping a fish with a sharp spine you might need to use multiple bags to ensure their safety as they can potentially puncture plastic shipping bags. Or use additional bags to separate them so that they won’t cause injury to other fish.

Travel Time

Getting the package as quickly to its destination as possible is your biggest priority when shipping live fish. The least amount of time your fish are in transit, the better.

Domestic Shipping

Overnight delivery, (normally arrives the next morning) priority mail, (arrives within 1 to 3 days) or priority mail express (arrives 1-2 days) is your best bet, but if this isn’t feasible, make sure you choose a delivery option that takes no longer than 3 days.

Any longer and the ammonia buildup in the water your fish are in are likely to reach toxic levels. Your fish will also be extremely stressed, which will make them more susceptible to illness and disease.

International Shipping

For international shipments or packages that will be sent overseas, try to choose the most direct flight, ideally in the early morning. This will ensure your fish get to their destination as quickly as possible.

Check for flights that have additional connections after the one you have organized. That way, if your original flight is delayed, your fish will be placed on the next flight.

Having live fish trapped during a connecting flight greatly reduces the chance of them surviving the journey, particularly in less than ideal weather conditions.


If you think your scheduled flight is going to be later or canceled, it’s better to reschedule the shipment than risk putting live animals in danger.

Temperature and Weather

In addition to travel time, you’ll also need to take the temperature and weather conditions into consideration when shipping live fish.

Check the weather forecast of your current location and your fish’s destination, alongside any areas your package will pass through during its journey.

Choosing the Best Day for Shipping

It’s best to select days that will be dry and slightly warm, with a temperature range of between 55 to 60 degrees Fahrenheit for both cold and warm water fish.

It’s actually beneficial to ship fish at their lowest preferred temperature range as cooler temperatures will decrease their metabolism. This reduces oxygen consumption, ammonia production, and carbon dioxide production, resulting in cleaner and less polluted water inside the bag.

Avoid shipping fish during extreme weather conditions…

Make sure to always check the weather forecast before shipping. Avoid shipping fish during extreme weather conditions, such as snowstorms, heatwaves, and heavy rainfall as your package could be delayed or may reach suboptimal temperatures, which will affect the health and survivability of the fish.


Man Moving Packages for Delivery Using Hand Trolley
Man Moving Packages for Delivery Using Hand Trolley

Another factor you need to take into account when shipping live fish is movement and handling during transit.

While you can’t completely avoid your package being tossed or thrown around during shipping, you can reduce its movement by using a strong and sturdy cardboard or Styrofoam box, double bagging fish, and using a packing material such as brown paper, packing peanuts, newspaper, etc.

And don’t forget to add labeling on the outer box with “fragile” and “contains live animals” stickers.

The latter will help the post office and couriers know how to appropriately handle the shipment (hopefully!).

Ammonia and Carbon Dioxide

As your fish will be in a small sealed bag containing water for a day or even longer, ammonia and carbon dioxide levels will rise. Ammonia is a natural waste product of fish – it’s excreted through the gills and is also present in their urine and feces.

There are two forms of ammonia that exist in water: ionized (NH4+) and un-ionized (NH3). Ionized ammonia is much less harmful than un-ionized ammonia. As the pH and water temperature decrease, so does the un-ionized form of ammonia.

CO2 or carbon dioxide is produced when fish breathe and can quickly reach harmful levels in a sealed shipping bag. Provided dissolved oxygen in the fish bag is high when the fish are packaged, it’s unlikely that your fish will suffocate during transit unless there are delays to the shipment.

…fast the fish 24 hours before they are due to ship to limit the amount of waste they produce.

One way to manage ammonia and CO2 levels in a closed bag is to fast the fish 24 hours before they are due to ship to limit the amount of waste they produce.

You should also take care not to overstock the bag with too many fish, otherwise, the biomass will be extremely high and more ammonia will be produced.

Additionally, if one or more fish die during transit, the body will begin to decompose, which will cause ammonia levels to spike.

Lastly, use pure oxygen instead of atmospheric air and ensure the shipping water is at the lower end of your fish’s preferred temperature range to decrease their metabolism.


You could also put buffers in the shipping water to reduce the effect of CO2 and pH, as well as an ammonia remover.


It’s important to maximize the amount of oxygen your fish receive while they are in a shipping bag or container, otherwise they will suffocate. This can be achieved by using pure oxygen or simply with atmospheric air.

However, if your fish will be in transit for a few days or you’re shipping larger fish/putting multiple fish in the same bag, I’d recommend adding pure oxygen to the top of the bag unless you’re using breather bags.


Breather bags are made from a permeable material that allows oxygen to enter and carbon dioxide to escape, so more oxygen is not needed.


Choosing a delivery option that offers tracking gives you and your buyer some peace of mind as you’ll be able to keep an eye on your fish’s journey, allowing you to update your customer if there are any problems such as delays.

You’ll also receive proper notification for when the package reaches its final destination.

Additionally, your buyer will also be able to see the estimated day and time their package is due to arrive so they can plan their schedule around the delivery.

As I mentioned earlier, the less time your fish are in transit, the higher the chance of their survival.

How to Pack Live Fish for Shipping

Writing A Note On The Box
Writing A Note On The Box

Now that you know the factors you’ll need to consider when shipping fish, let’s go over the things you’ll require to correctly pack your fish and prepare them for their journey.

Things You’ll Need

  • Plastic bag (designed for fish transport)
  • Rubber bands (to secure the end of the bag)
  • Outer shipping box
  • Insulated container
  • Pure oxygen 
  • Good-quality packing tape
  • Heat packs/cold pads
  • Packing material (newspaper, packing peanuts, etc.)
  • Ammonia remover
  • pH buffer (to stabilize pH of shipping water)
  • Treatment to reduce stress in fish such as API Stress Coat
  • Labels
  • Tranquilizers or sedatives (only if shipping large fish or delicate species)

How to Choose the Right Packaging

Plastic Bags

Use plastic shipping bags that are designed specifically for shipping fish. Bags should be at least 3 millimeters thick so they can tolerate being knocked without leaking. Better yet, double bag your fish to avoid disaster if one of the bags is punctured.

When shipping more than one fish, separating them using multiple bags is ideal. Shipping only one fish per bag helps increase the survival rate by reducing the dissolved oxygen consumption and fish waste in the bag. Another benefit of shipping only one fish per bag is that it can help reduce casualties if a fish dies or a bag gets punctured.

Most fish transport bags have a single bottom seal that can form sharp corners when packed with water.

Small fish can easily become trapped in these corners during the shipping process, so you can soften these corners by folding each side up, then taping them to the side of the bag.


Alternatively, you can use square-bottom bags that stay flat even when filled with water, but these are usually more expensive.

Rubber Band

You’ll need a rubber band to secure the end of the bag to prevent any leaks. I personally use two rubber bands for each bag for a bit of extra security.

Outer Shipping Boxes

Select a strong, sturdy corrugated cardboard box that can withstand heavy handling. Make sure it is large enough for the size of your fish but not so big that there is an excessive amount of empty space.

Insulated Boxes

An inner shipping container that offers insulation such as those made from polystyrene Styrofoam helps keep the fish inside at a consistent temperature.

It also provides your fish with some protection during transit, softening the blow of heavy handling or the shipping box being knocked over.

Packing Material

You can purchase packaging materials like bubble wrap, polystyrene balls, packing peanuts, etc, or you can make your own/recycle old packaging materials to save some money.

…scrunched-up or shredded newspaper/cardboard makes a great insulating and protective material…

For instance, scrunched-up or shredded newspaper/cardboard makes a great insulating and protective material for your fish transport box.

Heat/Cool Packs

Heat/cool packs will help maintain the temperature of the bag water while your fish are in transit, particularly during severe weather conditions.

You’ll need to consider the preferred temperature range of the species you’re shipping and the climate/weather during shipment.

For instance, if you’re sending tropical fish during cold weather, you’ll need to use a heat pack. Both heat packs and cool packs will eventually become depleted, so you need to choose one that lasts for the entire duration of your fish’s journey.


Make sure you don’t place heat/cool packs directly on the bag – either tape them to the underside of the lid or wrap them in newspaper.

Preparing the Fish

Betta Fish In Display Tanks and Plastic Bags
Betta Fish In Display Tanks and Plastic Bags

Once you have everything you need for packing your fish securely, you’ll now need to prepare them for their trip.

Don’t worry, I’ll be going over exactly what you need to do to get your fish ready for shipping in 8 easy steps.

Step 1: Decrease the Temperature of Your Tank

If you’re using a heater in your tank, gradually decrease the temperature to your fish’s lowest preferred temperature range over a period of 24 to 48 hours. This will help decrease your fish’s metabolism so they don’t produce as much waste during shipping.

Step 2: Fast the Fish a Day Before Shipping 

It’s best to withdraw food from your fish the day before you ship them to prevent fouling of the shipping water.

You should also check for any signs of illness/disease as you don’t want to post fish that are unwell. The stress from shipping could worsen their condition.

Step 3: Fill a Plastic Bag With 1/3 of Tank Water

On the day of shipping, fill a fish transport bag with 1/3 of tank water and add your livestock using a net. The water in the fish bag should be deep enough that it covers your fish’s dorsal fin when the bag is on its side.

Step 4: Add Ammonia Remover, ph Buffer, Stress Treatments, Etc

Add an ammonia remover or a water conditioner that detoxifies ammonia such as Seachem Prime. You can also add treatments such as API Stress Coat to protect your fish and keep them calm while they are in transit.

If you’re using pH buffers or sedatives/tranquilizers, you can also add these now. However, sedatives and tranquilizers are only really used when shipping large fish or sensitive species.

Step 5: Add Oxygen or Atmospheric Air

Once your fish are in the bag, add pure oxygen to the top and quickly tie the end into a knot, making sure to secure it with a rubber band. Alternatively, you can grab the bag quickly near the top to trap air inside or use a hand pump.


Don’t exhale air into the bag – this will fill it with CO2 and result in less oxygen for your fish.

Step 6: Place Another Bag Over the Top 

Grab a second shipping bag and slip it over the top of the first one for added protection and security. Tie the end into a knot and secure it with a rubber band.

Step 7: Add the Bag to the Insulated Box

Line the bottom of the insulated shipping box with newspaper or other packing material, then place the bag inside. Cover the bag with more packing material.


If you’re using heat/cool packs, either tape them to the underside of the lid or wrap them in newspaper.

Step 8: Place the Insulated Box Inside the Outer Shipping Box

Place the insulated box inside the outer box, then use a good quality packing tape to securely close the flaps. Add labels like “fragile” and “contains live fish” to the shipping box, alongside the recipient’s address.

Your fish are now ready to ship! Take the package to your nearest post office and choose your delivery option (ideally, one-day shipping or Priority Mail Express)

In case you need some more shipping tips, you can check out the video below.

How To Ship Fish

How Much Does It Cost to Ship a Fish?

The cost of sending fish via post depends on the delivery option, package weight, and the destination. For instance, Priority Mail for shipments below 70 lbs to any U.S state starts at $8.70. Priority Mail Express, on the other hand, begins at $26.95.

If your shipment is going overseas or is heavier than 70 lbs, the price of shipping will be significantly higher.

You’ll also need to take the cost of packaging and shipping supplies into consideration – fish transport boxes, packing materials, heat/cool pads, etc, will drive up the overall fee. 

Final Thoughts

I hope this article helped you learn the right method and tools to prepare fish for shipping.

The first time is always a little scary, so try not to worry too much. As long as you follow my steps above, you’ll be shipping fish like a pro in no time!

And after shipping, it’s important that the receiver knows what to do after receiving the fish, so be sure to let them know how to properly acclimate a fish upon arrival.

Feel Free To Share

If you know any other fish fanatics and aquarists, why not share this post on social media to help them know what to do when it comes to shipping aquatic animals!

(1) “Preparing for the move” by FWC Research is licensed under CC BY-NC-ND 2.0

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