How to acclimate fish to new freshwater tank?

Acclimating fish to a new freshwater tank is a crucial process that requires care and attention.

Whether you’ve just brought home some fish from your local store or received a shipment from afar, the acclimation process can vary depending on several factors.

There’s a widespread misconception that simply floating the bag in the tank for a few minutes and then releasing the fish into the water is sufficient.

In this guide, I’ll explore the steps involved in acclimating fish to ensure a smooth transition into their new environment.

Do you actually have to acclimate fish?

Fish are sensitive creatures, and abrupt changes in their surroundings can lead to stress or even fatalities.

To prevent such issues, it’s essential to acclimate them properly. The acclimation time can differ significantly based on various factors, including how long the fish have been in their bags.

If you’ve recently purchased fish locally, you may need to allocate only a short acclimation time, usually around half an hour. This brief period allows them to adjust to the new tank conditions without much hassle.

However, when dealing with shipped fish, especially those that have spent several days in transit, a more extended acclimation process is necessary.

These fish have been confined to bags where waste products like ammonia can accumulate, altering the water chemistry significantly.

When you first open the shipping bag, you’ll need to address the ammonia issue promptly. A product like Prime, which can detoxify ammonia, is highly recommended. It helps keep the ammonium in check, even as CO2 escapes, ensuring the fish are not exposed to highly toxic water.

For fish shipped in breather bags, avoid floating them to equalize the temperature, as this can block gas exchange and harm the fish. Instead, transfer them to a different container like a specimen container (Dip & Pour) and add Prime immediately to neutralize ammonia.

Now, let’s delve into the steps for acclimating fish to a new freshwater tank, whether they are from the live fish store or have been shipped.

Acclimate fish from the live fish store

To prevent your new pets from experiencing shock when you bring them home, start by dimming the lights.

Acclimating fish from the live fish store is relatively straightforward. Follow these steps:

1. Start by floating the bag in the tank water for about 20 minutes to slowly equalize the temperature.
2. Transfer the fish into a small bucket or, even better, a specimen container (Dip & Pour).
3. Slowly add 1-2 cups (200-500 milliliters) of tank water into the container, doubling the water volume. This gradual process will enable the fish to adapt to alterations in water pH, temperature, oxygen levels, nutrient concentrations, sounds, salinity, and lighting conditions.
4. Remove half of the water and discard it.
5. Repeat the process to double the water volume again.

Acclimate shipped fish

During lengthier journeys, like when fish are transported from breeding farms to pet shops, they might spend 2 hours to a few days in the bag.

In such instances, the fish’s respiration can cause a drop in water pH, leading to elevated ammonia levels.

Fish release waste in the bag, which decays into ammonia. They also consume oxygen and emit carbon dioxide (CO2).

As CO2 accumulates, it converts ammonia (NH3) into the less toxic form, ammonium (NH4+), safeguarding the fish during transit. This chemical process makes shipping fish feasible.

However, upon opening the bag, if CO2 escapes, ammonium can revert to ammonia, creating a highly toxic environment for the fish.

To counteract this, add a few drops of a water conditioner, like Seachem Prime, when opening the bag. It effectively detoxifies ammonia, keeping ammonium safe for the fish during acclimation.

Acclimating shipped fish requires additional care due to the build-up of waste and CO2 in the bags. Follow these steps:

1. Float the bag in the aquarium for 20-30 minutes to equalize the temperature.
2. Before opening the bag, have Prime ready to treat ammonia.
3. Transfer the fish and water to a specimen container inside a 3-gallon bucket to catch any overflows.
4. Set up an airline tubing from the aquarium to the specimen container with a control valve to regulate water flow.
5. Start a siphon and adjust the control valve to a slow drip, aiming for about one drop per second.
6. Double the water volume, remove half, and repeat this process two more times.
7. Finally, net the fish and place it in the aquarium, discarding the drip water.

Avoiding problems during acclimation

A significant cause of fish mortality in home aquariums is pH shock. Even seemingly minor pH variations, as little as 0.5, can be fatal for fish.

Their recovery depends on the severity of the pH difference, with greater differences increasing the risk of death.

To safeguard your fish, research the specific pH requirements for different species.

Additionally, be aware that water pH naturally decreases due to fish metabolism, necessitating regular water changes to maintain stability and restore alkalinity.

Your goal is to provide the best chance of survival for your fish. During transportation, the water in the bag experiences pH drop and increased ammonia levels.

Minimizing the stress of adjusting to different water quality conditions will promote the health and survival of your fish.

In conclusion

Acclimating fish to a new freshwater tank is not a one-size-fits-all process.

Fish purchased locally can be acclimated quickly, while those that have undergone shipping require more time and effort.

Regardless of the situation, patience is key.

By following these acclimation guidelines, you can ensure the well-being of your fish in their new aquatic home.