Article written by: Jason Danaher Ph.D.
Acclimation is the process of becoming accustomed to a new environment or to new conditions; therefore, acclimating your fish to the water in the tank can help decrease potential stress they would experience in the transfer process. Gradually allowing them to get used to the aquatic system’s water temperature, pH level and other water chemistry parameters can reduce any stress incurred by simply dumping them into the new system upon arrival and expecting them to adjust quickly. The acclimation process is simple and should take 30 to 45 minutes. Water quality (i.e. pH, unionized ammonia, nitrite, alkalinity, and total hardness) should have been tested the day before to ensure water quality parameters are within optimal ranges for the fish. Corrective measures through water exchange or supplementing proper additives orl compounds should have been done up to two hours before the fish arrival time.
The acclimation process should be performed when bringing your fish from an off-site location to your quarantine system. It can also be repeated when you transfer fish from individual systems located at your farm (i.e. hatchery to nursery, nursery to grow out, etc.). Below are general guidelines one may follow when fish arrive at their new system.
Fish arriving in a transport bag
Fish can be transported from one location to another using durable, clear plastic bags filled with water and oxygen for durations up to 36 hours depending on the fish species and water quality.
Figure 1. Fish arriving to your system in a transport bag:
1) When the fish arrive to your tank, do not open the bag (Figure 1). Place the bag in the tank water and allow it to float for 10 minutes. Ensure the bag of fish remains out of direct sunlight during the acclimation process.
2) Next, add some of your tank water into the bag – a few cups to start with. Allow the bag to remain floating for an additional 5 minutes. If the bag wants to sink, secure the bag to the tank’s edge. The bag should be left open, but do not allow your new fish to swim out of the bag yet. Monitor the oxygen concentration in the bag with an oxygen meter or continuously monitor the fishes’ behavior for piping at the water’s surface.
3) Repeat Step 2 by adding some more tank water into the bag; add the equivalent of an additional 25% of the bag volume from your aquatic system into the transport bag. Again, float the bag for 5 minutes, while securing the bag to the tank’s edge. The bag should be left open, but do not allow your new fish to swim out of the bag yet.
4) Then, repeat Step 3 by adding some more tank water into the bag every 5 minutes for a total of 15 additional minutes. If fish in the bag are found to be piping at the water’s surface then water exchange will need to occur more frequently or supplemental aeration provided/increased.
5) When the fish have been acclimated for 30 to 45 minutes, the pH is within 0.5 units, and the water temperature between the transport bag and the aquatic system is within 3 degrees Fahrenheit of one another, it is then generally safe to release the fish into your tank. Net them out of the bag gently and place them in the system. It is not advised to empty the water from the shipping bag into your aquatic system as it may contain fish metabolic wastes, chemical conditioners, and/or concentrated pathogens that would be detrimental to your aquatic system.
Fish arriving in a small (10- to 50-gallon) transport container
Fish may be transported in containers supplemented with pure oxygen depending on the fish size, quantity, and distance needed to travel from origin to your facility’s final destination.
Figure 2. Fish transported in a closed top tank with pure oxygen.
1) When the fish arrive to your aquatic system, add the equivalent of 10% the transport container volume from your aquatic system into the transport container.
2) After 5 minutes, add some more system water into the transport container; add the equivalent of an additional 25% of the transport container volume and wait an additional 10 minutes. Monitor the oxygen concentration in the transport container with an oxygen meter or continuously monitor the fishes’ behavior for piping at the water’s surface.
3) Repeat Step 2 by adding some more tank water into the transport container every 5 minutes for an additional 15 minutes, total. As the volume of the transport container reaches capacity, drain or remove some water from the transport container before adding more water from the aquatic system. If fish in the transport container are found to be piping at the water’s surface then water exchange will need to occur more frequently or supplemental oxygenation provided/increased.
4) When the fish have been acclimated for 30 to 45 minutes, the pH is within 0.5 units, and the water temperature between the transport tank and the aquatic system is within 3 degrees Fahrenheit of one another, then it is generally safe to release the fish into your aquatic system’s tank. Net them out of the transport container and gently release the fish into the aquatic system’s tank. It is not advised to empty the water from the shipping container into your aquatic system as it may contain fish metabolic wastes, chemical conditioners, and/or concentrated pathogens that would be detrimental to your aquatic system.
Similar steps can be used for larger aquaculture systems. Water exchange ratios and timelines can remain similar, but movement of water would be done more efficiently with an electrical pump. Feel free to call Aquatic Equipment & Design, Inc. staff at 407-995-6490 or email info@aquaticed.com if you have additional questions or require clarification.