How To Add Fish to an Aquarium

goldfish in plastic bag
Mark Fischer/Flickr

20 minutes is all it takes to safely acclimate fish to your aquarium.

Difficulty: Easy

Time Required: 20 minutes

Here's How:

  1. Test the pH, and chlorine levels before adding fish to a new tank. Chlorine must be zero, and pH close to that of the pet shop. Verify that the water temperature is at the proper level.
  2. Turn the light off in the aquarium to reduce stress.
  3. Lift the lid and place the sealed bag containing the fish in the water so it floats.
  1. Let the bag float for ten minutes, then open the top of the bag.
  2. Using the measuring cup, place one cup of tank water into the bag.
  3. Close the bag and allow it to float for another five minutes.
  4. Repeat steps five and six once. For sensitive fish such as neon tetras repeat two or three times.
  5. Place the small net into the bag, lift the fish out, and quickly transfer it to the aquarium.
  6. Discard the bag of water in the sink (never in the aquarium).
  7. Leave the light off for several hours to allow the fish to adjust to the new setting.


  1. If you only have a large net, hold the net over a bucket and gently pour the contents of the bag into it. Then quickly transfer the fish from the net to the tank.
  2. If there are already other fish in your aquarium place the new fish in a separate aquarium for several days and observe for disease.
  3. Brine shrimp nets are an excellent choice to transfer fish with.

What You Need:

  • measuring cup
  • small soft net