Best Way to Acclimate Fish To Your Aquarium

acclimate fish

All aquarium fish are sensitive to rapid changes in their environment. A sudden change can send them into shock and lead to death. We care about them so let’s do things the right way.

Floating bags from the store in your tank is not enough. Many people use this method, but this is wrong! It does nothing to acclimate your fish! All it does is adjust the water temperature of the bag to that of your tank. It does nothing for other water parameters.

Whatever how long you float the bag, if the water in it has a pH of 7.6, that will be a big shock for your new friend if you pour it into a tank with a pH of 8.3. Lights can overheat the water in the bag.

How to Acclimate Fish?

The following procedures help new fish to adapt nice and slowly to new water conditions. :


  1. As soon as you get home with new live stock, pour the bags into a water bucket. The bucket should be big enough, so the new fish is reasonably covered with the water. Don’t use new water or water from your tank! Just use the water that came with the fish. You may acclimate more than one fishes in the same bucket. Any poisonous, toxic, or aggressive animals should be acclimated individually.
  2. Now set the bucket on the floor next to the aquarium or quarantine tank.
  3. Using a plastic airline tubing, set up and run a siphon drip line from the aquarium to the bucket.
  4. This procedure must be really slow, so we now need to adjust the flow. This is where the air valve comes into play. Using the air pump or air valve, adjust the water flow coming from the tank to the bucket (A loose “knot” tied in the airline would do). Water should go through the airline one drop at the time (one drip per second is good). This way, the water that came with your new friend will slowly adjust to the tank condition.
  5. From here, things goes pretty much by them self. Let it drip for a good 30 min to 1 1/2 hours. Hardy fish should do well with shorter dip time while sensitive species might need more. Once this is done, test water in the bucket to see if water parameters match that of your tank water. If the answer is yes, the acclimation is complete.
  6. It’s now time to introduce your new friend to your tank or in a quarantine tank. Use the container that will submerge in the bucket and place the animal it. Then, remove the bowl with just a little water and your animal. Gently submerge the container into your tank or quarantine tank (do not throw or drop the fish from above the surface of the water).

Try to avoid adding water from the shipping bag to your tank. You don’t know what’s in it. It may introduce diseases or other undesirable things in your tank. The best is to throw out the water in the bucket. You may also turn off the lights and leave them off for 2-3 hours after the fish are introduced. This will help reduce stress.

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