How to Transfer Goldfish to a Bigger Tank

Goldfish, while commonly sold as "bowl" pets in retail chain stores, can be almost impossible to keep properly in these conditions. The misconception that goldfish can thrive in small, unfiltered containers has led to untimely death for many fish, and discouragement for many would-be goldfish enthusiasts. Many first-time fish owners find themselves faced with the task of relocating goldfish to a larger tank, but the experience does not have to be stressful for you or your fish if you follow some basic guidelines.

Things You'll Need

  • 20 gallon or larger aquarium
  • Gravel
  • Filter
  • Heater
  • Plastic container
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Instructions

    • 1

      Set up the new tank. A single goldfish should never be kept in a tank containing fewer than 20 gallons of water; add approximately 10 gallons of water for each additional fish. Rinse any new gravel thoroughly before you place it in the new tank. Use an aquarium heater to keep the temperature between 74 to 80 degrees Fahrenheit. Goldfish are very messy fish, so an adequate filtration device is essential. If you have a filter on your fish's old tank, pull out some of the filter media (sponge or bio-balls) and place it in the new filter. This will help supply the new tank with beneficial bacteria for the aquarium nitrogen cycling process. (See the Tip for additional information.)

    • 2

      Carefully catch the goldfish. While you can simply net the fish, scooping up the fish in a plastic container often works much better, especially for fancy or long-finned goldfish varieties. This prevents the fish's fins from becoming entangled in the netting, and also eliminates the stress of being removed from the water for a time. Use a plastic cup, a plastic container or a fish container meant for this purpose.

    • 3

      Allow the goldfish to acclimate to the container; this is the second benefit of using a container rather than a net. Place the plastic container in the new tank and let it float for 15 minutes. Add a small amount of new tank water to the container every few minutes for about 30 minutes, until the water in the container has doubled in volume. This way, the goldfish has time to adjust slowly to any temperature and water chemistry discrepancies between his old and new tank.

    • 4

      Slowly tip the container sideways and allow your goldfish to swim out into his new tank. Let him explore and adjust for about an hour with minimum disturbances. After this time, you can offer a small snack or meal to help your goldfish feel comfortable in his new surroundings.

    • 5

      Perform regular water changes of 10 to 20 percent each week.