When you have brought your new fish home in their plastic bag, take care when introducing them to your aquarium.  Fish become stressed when their environment changes, so it’s important to help them transition smoothly to their new home.  Here is an easy to follow, step-by-step guide on how to acclimatize new fish to your aquarium.

1. Turn off the lights in the aquarium

Start by turning the lights off. This helps to lower the stress of the new fish, and reduces potential bullying in the tank.

2. Float the plastic bag in the aquarium

Float the bag in the aquarium water for at least 10 minutes. This is to allow the temperature of the water inside the tank, and the water inside the bag to equalize.

3. Undo the plastic bag

Carefully untie the knot if possible (or carefully cut the bag just below the knot) and very gradually introduce the water from the tank into the plastic bag, over the course of about 10 minutes. This method allows the fish to adjust to the water chemistry of your aquarium, which may differ to the water in the bag. This is to prevent shock and is an important step in how to acclimatize new fish to your aquarium. It is worth testing the chemical balance of your aquarium water every and now and then, various water treatments and test kits are available.

4. Immerse the plastic bag

Once the 10 minutes has passed, very slowly lower the plastic bag until it is completely immersed. You should continue to hold the bag and allow the fish to swim out of their own accord. You must then remove the bag.

5. Turn the lights on

Once the new fish is swimming in the aquarium, wait for about 30 minutes. The new fish should now be acclimatized to your aquarium.  The lights can be turned back on, and you may give the fish a little food.