The Kordon Breather bag is by far the only choice when shipping fish across town or across the ocean. Kordon Breather Bags are available in various sizes and made of a special membrane material. The membrane allows oxygen to enter the bag and carbon dioxide to be released by friction, much like the gill functions of a fish.
I have been using these bags now for about two years and have only lost two or three of the hundreds of fish I have shipped to people. I have received many breather bags full of livebearers that were dead on arrival. Each time the deaths are caused by incorrect use of the bags due to inexperience or bad advice. One common problem is double bagging. Yes, on the bag it says that you can double bag them without fail, however that was an error.
Upon contacting Novalek, Inc. (the owner of Kordon products) I was told that there was only one production of over one million bags. Once the bags were on the market, double bagging was found to lessen the gas exchange, if not stop it completely. There was only one instance that I received a double bagged breather that contained live fish. The reason was that the sender had poured water between the two bags that allowed gas exchange through each membrane. Another common reason for the bags to fail is air left inside the bag. There should be only water inside the finished bag. Also, Unlike poly bags, you cannot ‘float’ breathers, the lack of air around the bag will also stop all gas exchange.
