by Frank Cowherd
Everyone who has been in the aquarium hobby for any time probably has developed their own procedure for transferring new fish to their tank. If you have a procedure that works for you, use it. If not, here is the procedure I recommend. Fish may be shipped in regular bags or in breather bags. Breather bags contain less water than regular bags. This procedure is fine for either type of fish bag.
Transfer all fish or daphnia and as much water as possible from the bag to an empty acclimation container that will result in a water depth of at least a half inch. (Since breather bags contain less water than regular bags, their acclimation container needs to be smaller to provide enough water depth to allow the fish to swim normally.) Then using water from the tank you are going to put the fish in, double the depth of the water. Wait for 15 minutes, and then double the water level again. Wait at least ten minutes and repeat. Then using a net, catch the fish and place it or them in the desired tank. If there is not enough room in the container to double the level the second time, drain out half the water, and then double the level.
This procedure acclimates the fish to both the temperature and the water quality of your tank. The fish are normally shipped in water that is at a pH above 7. If your water is very acidic (<= pH 6.5), you might want to use less water for each step and add a few more steps in the acclimation process since that would give a more gradual pH change for the fish to adjust to.
Use scissors to open the bag along the whole top of the bag. You need a large opening to get the fish out easily and to get the most water out of the bag.
Do not worry about the fish being on their sides in the acclimation process, but try to minimize their darting about by placing them where they cannot see motion outside of the container. In fact, use an opaque container or cover them with a dark cloth. A coffee cup works well for a single fish received in a breather bag. Warm the cup in your fish tank prior to use.
More about breather bags: Breather bags allow oxygen to pass through the bag so the fish have a virtually unlimited supply of oxygen. They also allow carbon dioxide to leave the bag, so the fish are not living in water that slowly goes acidic. There is no need for an air space in the bag. Without the air space there is no splashing. Probably the fish benefit from no splashing since that action/noise can make them excited. For breather bags shipments, fish require only a small amount of water. This is beneficial in that oxygen and carbon dioxide have less distance to travel to get into or out of the bag. However, fish (like corydoras and gouramis) that breathe air can be shipped in breather bags with an air space. Note: Breather bags should never be floated or placed in water to acclimate since that prevents oxygen exchange and can kill the fish
Disregard the above procedure if the shipping water is very bad, e.g. it is very cloudy and contains a lot of debris. In that case it is actually best to catch the fish in a net and add it directly to some of your tank water in a small tank. This gets the fish out of the polluted water quickly and gives them a better chance to survive.
April 25, 2011