How to Add Fish to an Established Aquarium

The idea of stocking an aquarium may attract you if you are searching for a low maintenance pet. You will need to do some periodic maintenance and take special care when adding new fish to your aquarium. Being introduced into a new aquarium is a stressful event for a fish. It has likely just been scooped up in a net, taken out of the water it is accustomed to and transported before being dumped into a different environment with new tank mates and possibly some unseen diseases.

Things You'll Need

  • New fish
  • Net
  • Cup
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Instructions

  1. Prepare the Tank

    • 1

      Prepare your tank for new fish by ensuring there are plenty of places for the new fish to hide, such as rocks and plants. Rearrange what you have to remove territories and distract the existing fish. This will enable it to run from aggressive fish and find security.

    • 2

      Add more than one fish to reduce the risk that any existing fish will harass a single new fish.

    • 3

      Feed your existing fish before you put the new fish in the tank. This will make the existing fish less aggressive toward their new neighbors.

    Adding New Fish

    • 4

      Place the closed bag with the new fish in the water. Leave the fish in the bag and allow the water temperature in the bag to change to that of the tank water.

    • 5

      Open the bag after 15 minutes and clip the bag to the side using a metal clip or roll the edge of the bag to create an air pocket so the bag will float.

    • 6

      Add 1 cup of aquarium water to the bag every 15 minutes for 30 to 45 minutes, so that the fish become accustomed to the tank water.

    • 7

      Use a net to gently lift your fish out into the aquarium water without introducing water from the bag into the aquarium.

    • 8

      Remove the bag and discard the water.