How Long Can Fish Live in a Bag?

fish in the plastic bag

As a beginner at rearing fish in a tank, it is important that you know the answer to this question – because it’s likely that you will get your first fish inside a small bag. From a small bag, you can transfer the fish into a tank, once the tank is prepared and ready.

How Long can a Fish Live in a Bag? A fish will live comfortably in a bag containing water for between 7 and 9 hours. Many fish pet stores will add more oxygen into the bag, meaning that it can survive for up to 48 hours. The survival of the fish will depend largely on the amount of air inside the bag.

Fingerlings or small fish are normally transported inside a sealed plastic bag containing water and oxygen. In most cases, 1.5 to 2 gallons of water is required.

The polythene bag should be 3mm thick, and should measure at least 18” wide x 32” high.

Excess air must be removed from the bag and replaced with pure oxygen. The bag itself must be sealed and placed in an insulated container before being transported to the tank in a cardboard shipping box.

Can You Transport Fish in a Ziplock Bag?

Do you wonder if you can transport fish in a ziplock bag? The answer is yes, but a fish must not stay inside a Ziplock bag for more than 30 minutes. It’s also crucial that the bag is clean, and doesn’t have any holes. Make sure it is the biggest ziplock size, and don’t put more than one fish in the bag.

How well a fish survives inside a bag also depends on the water quality.

Do not leave the ziplock bag upside down as the waterproof seals may open up and cause air leakages – and this could expose the fish to serious danger.

Not all ziplock bags are good for transporting fish – poorly designed bags may leach chemicals into the water, causing pollution.

If you are transporting a salt-water fish, you may have to reduce traveling time from 30 minutes to about 15 minutes. Saltwater is quickly polluted with chemicals leaching from the bag.

Fish must not spend much time inside a ziplock bag because the seal may collapse at any time, causing a depletion in oxygen. Ziplock bags are also notorious for leaking, exposing fish to serious danger.

In addition to air leakages, the zipper may fail and that could further deplete the oxygen left inside.

How Long Can Fish Survive Without Oxygen?

Are you worried about how long a fish can survive without oxygen? The answer is TWO DAYS! when the fish is in shallow water, its movement will force the water to circulate, which in turn can help the fish pick up some oxygen from the surface.

A fish can survive in shallow water conditions for about 2 days, and may even live for up to a week if it is the only fish in the container. In a crowded situation, fish will compete for more oxygen, which will lead to a depletion of the gas – meaning that they may not last for 2 days.

Can a Fish be Transported in a Closed Container?

Small fish and fries can be killed when transported inside a closed container. Bags are the ideal choice for transporting smaller fish, because of their economic advantages over closed containers – and this is particularly the case where there are long distances involved.

A fish can remain in a closed container for not more 2 hours. After this time, the conditions will become unfavorable – for example, the pH levels may decrease or increase sharply after the first hour inside a container.

The fish may also quickly deplete its available oxygen. For this reason, and to avoid distress, really a fish should not be kept inside a container for longer than 40 minutes.

How Long Can Fish Live in a Bag with Oxygen?

A fish can survive inside a bag containing sufficient oxygen, for about 2 days. It is important to note that regular atmospheric air inside a bag does not contain enough oxygen. Fish pet stores add pure oxygen to the bag to keep the fish alive – they do not use atmospheric air.

The fish inside the bag must be exposed to a minimal level of stress, especially during transportation. Once a bag is sealed, a fish may become restless and consume more oxygen than necessary and in this situation, transport time must be reduced.

Child putting new fish in an aquarium

How long do you leave the Fish in its Bag for when transferring it into the Tank?

You should leave a fish in its bag for no more than 20 minutes before releasing it into the tank. In order to transfer the fish into the tank, simply hold the bag inside the aquarium and let it float, unopened, for about 20 minutes.

At this time, you can also make any necessary changes to your tank – for instance, you may want to rearrange the decorations and the water components.

Once the bag is floating on the surface of the tank, carefully open the bag and use a cup to scoop some water from the tank into the bag. Never pour the entire water in the bag into the water in the tank.

Add an equal amount of water in the tank into the bag and now you will have doubled the initial water in the bag. Make sure you close the hood on the edge of the bag to prevent water spilling out.

Now that the fish has gotten used to 50% water in the tank and 50% water in the bag, you can introduce the fish fully into the aquarium after it has spent a further 20 minutes in the bag.

Sit back and watch how the fish reacts for about an hour. If your fish starts to scratch its body against plants or other components in the tank, it may suggest that the water is more alkaline than it’s used to, and you may have to replace at least 20% of the water with clean, fresh water.

Do not feed the fish with food immediately after transferring it into the tank – feed it after a few hours when you can see that it has fully adjusted to its new environment with no negative reactions.

Extending the Lifespan of Fish inside a Bag before Transferring the Fish into the Tank

In order to protect your fish inside a bag during transportation, you need to ensure that the right temperature, dissolved oxygen, and carbon dioxide levels are maintained.

You need to keep in mind that nitrogenous wastes such as ammonia compounds are toxic to fish, even at low levels. Since fish excrete ammonia from the gill membranes in order to eliminate ammonia compounds, you need to reduce travel times.

Ammonia waste can also negatively affect the pH and temperature of the water inside the bag. You can prevent ammonia waste from the fish by avoiding feeding it while it’s inside the bag. Ammonia will increase the alkalinity of the water inside the bag, and that could be catastrophic to freshwater fish.

It is also important to keep the water temperature low while the fish is inside a bag in order to reduce its metabolism. Ammonia in the water will increase the temperature, and an increase in temperature is known to speed up the metabolism in fish – meaning they may soon get hungry.

The type of bag you use must be at least 3mm thick for the ideal seal and to prevent damage. Make sure you avoid the pillow-slip bags because they can create sharp corners when filled with water. Sharp corners can become a trap for a fish, meaning that it might choke and die.

If you have to transfer the fish in a pillow-slip bag, you can square up the bag corners by simply folding them up and then tapping to the sides to prevent square corners.

Some fish bags may come with square bottoms so that they can sit flat at the bottom of a transporting box. These flat or square bottomed bags tend to be more expensive but they are much safer because they don’t trap the fish.

Fish bags can be punctured during shipment or transport and this must be avoided at all costs. When you are transporting a fish that has a sensitive, sharp spine, you may need between 2 and 3 extra bags to ensure that at least one bag remains watertight at all times.

Once the bag has been filled with clean water and dissolved oxygen, it must be sealed carefully. You can make use of rubber bands to twist and tie the top but make sure the rubber bands are good quality – you don’t want them to break.

If you have to transport the fish bag in boxes, then the boxes must be insulated, in order to keep temperatures inside the bag constant during transport.

Do not add antibiotics into a fish bag during transfer – such medications can do more harm than good. Remember that the fish is nervous inside the bag, hence it may use up more oxygen. You need to ensure that you add more than enough oxygen that will last beyond the duration of travel inside the bag.

It is recommended that the fish bag contains no less than half of its volume in Oxygen. And in fact, many pet stores seal the fish bag with two-thirds of oxygen inside.

You may use heat or cold packs when necessary, in order to maintain the correct temperature. In extreme winter conditions, there are special heat packs that release more heat when exposed to oxygen, but these packs will stop working once the oxygen inside the container box has been used up.

If you are transporting your fish for less than 40 minutes, you may not need heat or cold packs, however, these packs can help regulate temperatures for several hours. Temperature-controlling packs must be added into boxes and not into the fish bags.

Fish pet stores can provide you with pH buffers to ensure that the pH of water in the fish bag is properly maintained. Since carbon dioxide levels increase inside the fish bag during transportation, this will eventually lead to a drop in pH levels. In most cases, carbonates or bicarbonates are added as pH buffers inside the fish bags to keep alkalinity optimal.

It is important to prepare a fish for any trip that will last for more than 40 minutes. The type of preparation used will depend on the species of the fish.

Make sure that only healthy and robust fish are chosen – they must have been certified to be healthy enough to make a trip. The fish must be prepared in well-aerated water before being transferred into the bag.


In conclusion, a lot of preparations are involved in the successful transfer of a fish inside a fish bag. First and foremost, if you are transferring a saltwater fish in a bag, you need to prepare your aquarium to host a saltwater fish. This same rule applies if the fish species is a freshwater fish.

Secondly, it is important to transfer one fish at a time inside a fish bag. Having two fish in a bag at once may lead to serious problems. Two fish mean that the pH levels will decrease or increase even faster. It also means more oxygen will be used at a faster rate.

Taking the fish one at a time will also prevent predatory attacks, especially from an aggressive fish on a gentler fish.

The most important point to note is that the transportation of fish inside a bag must be reduced as much as possible, to minimize the likely side effects of adverse temperature changes and rising carbon dioxide.

Saurabh Kumar

I am a passionate fish keeper, with years of experience in my hobby. You will find some really useful tips and information that I have learned along the way.

Leave a Reply

Your email address will not be published. Required fields are marked *

Recent Content