Shipping & Acclimating Fish

Fish bagging for shipping and auctions
Shipping fish successfully is easier than you think. The key is to purge the fish before they are bagged, so they do not die in their own waste. The night before you bag them up for an auction or shipping, catch the fish from the tank and place them with some tank water in a covered bucket or plastic shoe box at room temperature. As long as there are not too many individuals, no air stone or filtration is required. The stress from the catch and the strange environment will cause the fish to relieve themselves. The slow drop in temperature overnight will slow their metabolism. By the next morning, the water will be all filthy, however the waste won’t end up in the bag because for bagging I always use 100% clean new water from an empty tank or tub also kept at room temperature. Add a few drops of a Ammo-Lock or similar to the bag to bind any new ammonia the fish will release. Fish bagged that way will travel much better and adapt easier to a new environment.

Fish acclimatization
The common advice is to float the bag with your newly arrived fish to adjust the temperature but that makes no sense at all. Why am I saying that? Well-packaged fish can survive 2-3 days in a bag without any problems. The water may be cold and a bit filthy, but the metabolism of the fish has slowed down because conditions in the bag have worsened gradually and they have adapted. When you warm up the dirty water, the metabolism kicks back in and the fish get terrified due to the light and warmth. If the bag remains closed, low oxygen levels may now lead to suffocation because the fish panic and use more oxygen. In normal fish bags there is also an excess of carbon dioxide (CO2), which means that the pH has dropped slowly because of the continuous formation of carbonic acid (CO2 + H2O = H2CO3). However, as soon as you open the bag, the CO2 escapes quickly and the pH can rush up from below 6 to over 7.5. If there is any ammonium (NH4+) present, it will quickly turn into ammonia (NH3) that burns the gills, fins, and skin of your fish. The higher the temperature, the faster this process becomes.

A better way
When you unpack, pour the fish immediately with some transport water into an open container so their bodies are covered (careful, some may jump out). Then add water from the new tank using a cup so that the temperature is barely increasing. If the transport water is very cold (<60 °F), use cold water for the change. The point is to replace the transport water with all the filthy stuff quickly and then bring the temperature up slowly by either waiting or gradually adding warmer water. Once the temperature is within 3-4 °F, take a net and move the fish to their new home. Discard all the transport water. You will rarely lose fish that way. The slow process also allows for the pH to gradually adjust without shocking your new arrivals. Note: sturdier fish can be moved without adapting at all if the temperature and pH are not too far apart (within 5 °F/0.2 pH difference): just net them out of the transport water and move them to the tank or container. If the pH differs by more than 0.3, adjust the pH in the tank or container first by adding some acid (e.g. pH minus from Sera). Once the pH matches the bag water, move the fish.

Last modified: January 30, 2016 at 3:31 pm