I recently sent fish out to three people. I sent the fish first thing Monday morning via USPS priority. Each box was lined with 1.5” tight fitting polystyrene sheet. The temperatures were rather cool (upper 70’s to low 80’s) where the fish were delivered.

I used aged, aerated, dechlorinated and salted water from 24 hours prior to packaging. I used breather bags. Before each bag was sealed I put a little squirt of Amquel in each bag. Once I started to pack the fish I felt the boxes were a little cramped (each bag touched). It seems I under-estimated the 1.5” thick polystyrene sheet and reduced my overall capacity too much. I didn’t have time to make new boxes and the fish were shipped. All fish arrived at their destination on Wednesday. Most fish did not make the trip.

How much air space should be present in the box when using breather bags?

Is it harmful if the bags touch while in transit? If so, what’s the best way to prevent them from touching each other?

Please tell me what I’m doing wrong (chemical shipping supplies, mechanical packing problem etc.) as I obviously need to improve my shipping skills.

I wouldn’t post this if this was the first problem I’ve had with sending fish.

Thanks in advance.

A couple of points. Some of these are probably way off, but I will suggest them anyway.

First off, I am leery of taking fish out of a holding container and placing them directly into "new" water. While putting fish from relatively clean water into water of questionable integritycan cause problems, I have found the same is true of the opposite. I am certainly not suggesting your holding containers have quaestionable water, but it could be just different enough.

When preparing the bags for shipment, we always wrap them in a few sheets of newspaper. This acts to buffer the bags from each other. This might not be important when using conventional bags, but with breather bags, I think it's essential. If the bags are pressing against each other, this effectively eliminates that surface area from exchanging gases. Some have questioned newspaper since it may get soggy if it gets wet from a punctured bag, but e have never had a problem. An effective alternative is styro peanuts. I am concerned that the weight of the bags may cause them to gather in the bottom of the box and end up touching each other with this method. If you do use this method, be sure to go with the styro peanuts vs. the cellulose ones since those will dissolve if they get wet.

I'm not certain what you mean by how much air space should be left in the bow. I assume you meant box. If so, air space in the box is not terribly important. We routinely pack boxes fairly heavily with no discernable air space, except for the created by the bunching of the newspapers.

First off, I am leery of taking fish out of a holding container and placing them directly into "new" water. While putting fish from relatively clean water into water of questionable integritycan cause problems, I have found the same is true of the opposite. I am certainly not suggesting your holding containers have quaestionable water, but it could be just different enough.

Interesting....My holding tank (or home tank in this case) naturally had some nitrates (about 25 ish) and I did use what I would describe as "new" water. I always make sure the salinity is correct with the new water but I naturally don't add nitrates. This make sense. In this case I took the fish from an established tank and dropped it in "new" water adding stress to an already stressful travel. I'll use the tank water to ship next time.

When preparing the bags for shipment, we always wrap them in a few sheets of newspaper. This acts to buffer the bags from each other. This might not be important when using conventional bags, but with breather bags, I think it's essential. If the bags are pressing against each other, this effectively eliminates that surface area from exchanging gases. Some have questioned newspaper since it may get soggy if it gets wet from a punctured bag, but e have never had a problem. An effective alternative is styro peanuts. I am concerned that the weight of the bags may cause them to gather in the bottom of the box and end up touching each other with this method. If you do use this method, be sure to go with the styro peanuts vs. the cellulose ones since those will dissolve if they get wet.

I've never wrapped breathing bags in paper but I've never had very good success either. I've always been concerned about the bags touching (surface area excahnge) but didn't know exactly how to deal with it.

I'm not certain what you mean by how much air space should be left in the bow. I assume you meant box.

Good assumption on your part and bad proofing on my part.

In this case I overpacked the box (no room for wadded up newspaper), the bags were touching and I used "new" water. Duh...


Thank you very much for your help. I think I might perform a few tests the next time I come across invasives just to check the limits of these bags

If the bags were packed tightly into a box with nothing buffering the bags, then I am confident lack of O2 is your culprit. Some of the bags might not have been able to exchange at all(if they had bag to bag contact on all sides).

I originally placed the bags upright. I happened to be on the phone when one of the recipients opened the box. He indicated they were stacked on top of one another. I'm sure that wasn't good.

I feel a bigger box could have helped here even without the paper buffer knowledge.

I will change my ways.

Thanks again.

"I've never wrapped breathing bags in paper but I've never had very good success either. I've always been concerned about the bags touching (surface area excahnge) but didn't know exactly how to deal with it. "


We have been using the breather bags and enjoying them! We use clean well water that is about the same temperature of the fish that are to be shipped. Remember to sit your fish in buckets for 24 hours so they have time to get rid of waste before you ship them. Wrap each individual bag in a piece of newspaper. Make sure you are not using the plastic-like newspaper.. this will not allow enough air to get to the fish.Then pack in extra wads of newspaper just enough so they do not roll constantly. This has worked for us for many shipments with no problems.

Brian and Julie Zimmerman

Fasting your fish for 24 hours is the minimum. For long gut fishes [mainly plant/algae eater] longer fasting time is need, 2 days perhaps. Fishes can usually withstand a week without food so it's better to be safe and make sure they travel with empty gut

Update:

I now use tank water (instead of aged & dechlorinated) tapwater that has Amquel plus added two or more hours under strong aeration. I make sure the fish are wrapped better than in the past (a bit tighter). I also use less water and make sure give the bags a little room instead of packing them tightly. I believe all of these changes have greatly improved my shipments. I've shipped hundreds of fish between the time I've posted this topic and now, with only one fatality.

Fasting your fish for 24 hours is the minimum.

Tricolor, I fully agree. I fast the fishes to be shipped for 48 hours just to be sure. Swimming/breathing your own waste simply can't be good for them.

I'm not a fan of breather bags because the availability of oxygen is just one issue. Fish need oxygen and the breather bag is supposed to transport oxygen through the bag in the environment that it is placed. Think about it, if you wrap the bag in newspaper, there is little to no air available for O2 transport. If the newspaper is wet there is even less O2 available because the wet paper will form a seal around the vapor bag.

If the bag is full of water with no air then the O2 must flow directly into the water. If the bag has a large amount of air then O2 can flow into the breather bag into the air and into the water. I'm not sure if a breather bag is considered to be a semipermeable membrane or not. If it was O2 would be transported across the membrane from high areas of concentrations to low areas. This would help drive the transport. But as I mentioned above O2 has to be readily available to be transported.

Another issue is heat. Heat can easily be transfered and maintained in a breather bag with little to no air regardless of wether insulation is used or not. The fish by their activity and metabolism generate heat which would be maintained more in a small volume breather bag with little to no air. The use of wet newspaper could cool the bags as the water on the newspaper evaporates but this would interfere with O2 transport.

The use of an ice pack makes huge sense to me. They are cheap and quite effective. I have used them for years to transport bacteria in an cold inactive state from environmental locations.

Large plastic transport bags with lots of air and little water to me make a lot of sense. Water saturates the air cooling the water. O2 saturates the vapor etc. The volume of the bag is large enough to discourage heating and easier packing. Wet newspaper can be used for cooling. Ice packs can be used.

Living on a mountain top surrounded by desert all my natives are imported. I have lost no fish transported in large bags with lots of air even when shipped from Florida by US mail express. Ninety percent of fish shipped in breather bags by UPS next day have not survived the trip.

In another post I will suggest a test to see which method is best.

I'm not a fan of breather bags because the availability of oxygen is just one issue. Fish need oxygen and the breather bag is supposed to transport oxygen through the bag in the environment that it is placed. Think about it, if you wrap the bag in newspaper, there is little to no air available for O2 transport.

This analysis notwithstanding, the method works.

If the bag is full of water with no air then the O2 must flow directly into the water. If the bag has a large amount of air then O2 can flow into the breather bag into the air and into the water. I'm not sure if a breather bag is considered to be a semipermeable membrane or not. If it was O2 would be transported across the membrane from high areas of concentrations to low areas. This would help drive the transport. But as I mentioned above O2 has to be readily available to be transported.

Yes, it is a semipermeable membrane. Aside from that, the breather bag/newspaper system works!

Another issue is heat. Heat can easily be transfered and maintained in a breather bag with little to no air regardless of wether insulation is used or not. The fish by their activity and metabolism generate heat which would be maintained more in a small volume breather bag with little to no air. The use of wet newspaper could cool the bags as the water on the newspaper evaporates but this would interfere with O2 transport.

I can't see evaporation having much of a cooling effect. The air in the box would quickly become saturated and then you have no more evaporation. Other than that, I don't follow your anaylysis of why bags with air in them in inherently cooler than bags with just water. I would think that whichever packing method has more thermal mass (=water) would have the stablest temperature (and costliest to ship).

Large plastic transport bags with lots of air and little water to me make a lot of sense.

That system works as well. Plus the bags are cheaper

This analysis notwithstanding, the method works.
Yes, it is a semipermeable membrane. Aside from that, the breather bag/newspaper system works!
I can't see evaporation having much of a cooling effect. The air in the box would quickly become saturated and then you have no more evaporation. Other than that, I don't follow your anaylysis of why bags with air in them in inherently cooler than bags with just water. I would think that whichever packing method has more thermal mass (=water) would have the stablest temperature (and costliest to ship).
That system works as well. Plus the bags are cheaper

15 out of 17 dead does not equal work well it equals works poorly to not at all.

15 out of 17 dead does not equal work well it equals works poorly to not at all.

I know myself and several others have successfully shipped 100's of fish with breather bags with no problems. In most situations breather bags function like they are supposed to. In some cases, like yours, the other method is better. But just because you had bad experiences doesn't make the product flawed. If a shipper won't ship to you with oxygen, then don't get fish from them.

I have shipped 1000's of fish using the breath bag/newspaper method and have been extremely pleased with the outcome. The only time I choose not to use breather bags is when I have a large spiny fish like an adult catfish or sunfish. Sometimes, in this case, I just double bag with the breather bags which works quite well. You just have to be certain that you do not get any water between the two bags. If you do, you are essentially sealing off the inner bag and not allowing an gas exchange. I do have an O2 cylinder that I have used twice, I think. It is just too much trouble and the bags take up too much space in the box.

I know myself and several others have successfully shipped 100's of fish with breather bags with no problems. In most situations breather bags function like they are supposed to. In some cases, like yours, the other method is better. But just because you had bad experiences doesn't make the product flawed. If a shipper won't ship to you with oxygen, then don't get fish from them.

I think in my case what got the fish was temperature. Higher the temperature the less dissolved oxygen. For breather bags the heat mass per unit volume is greater than the other method and it appears in the summer this could b a problem in the warmer areas of the country. UPS also uses trailers for temporary storage and shipping, even for next day deliveries. The Post Office does not. These trailers can reach 140 degrees.