How to Stock a 20 Gallon Aquarium

Adding an aquarium to your home or office is an excellent way to bring the beauty of nature into your home, but it is important to stock that tank properly. Many beginning aquarium hobbyists make the mistake of putting too many fish into too small a tank, and this mistake can have serious consequences for both the health of the inhabitants and your enjoyment of the aquarium.

Things You'll Need

  • 20 gallon aquarium
  • Water test kit
  • Plants and rocks
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Instructions

    • 1

      Obtain a sample of your aquarium water and use a water test kit to assess the quality of the water. These test kits are available at most pet stores and aquarium stores, and they are used to determine the level of hardness in the water, as well as the presence of potentially harmful elements like ammonia and nitrates. You may also be able to have your local pet store test the water for you.

    • 2

      Go to your local pet store and look at the fish they have for sale. This will give you an idea of what type of fish you want to stock in your aquarium. When shopping for fish, keep in mind that many species are schooling fish by nature. If you choose one of those it is important to purchase at least three or four so they can exhibit their natural schooling behaviors.

    • 3

      Choose between setting up a community tank or a specialty tank. With a community tank you would choose a number of peaceful species that interact well together. Leopard danios, zebra danios, tiger barbs and tetras are all good choices for a community tank.

      If you choose a specialty tank you will specialize in one type of fish. Cichlids are a popular choice for specialty tanks due to their interactive nature and the wide number of varieties available. Many cichlids tend to be a bit aggressive, so they may not be right for a community tank. They do well, however, in a species-specific tank.

    • 4

      Prepare your tank by adding plants, rocks and driftwood. This will make the tank look more natural and provide plenty of hiding spaces for the shyer fish in the tank. Providing hiding places is important, since fish will use rocks and plants to hide from predators and more aggressive fish in the wild.

    • 5

      Limit the number of fish you purchase to a number your tank can sustain. A good rule of thumb for beginning hobbyists is to limit the amount of fish to one inch of fish length per gallon of water. So a 20 gallon tank would be able to sustain 20" in total fish length. If you choose small species with a maximum length of two inches, you could stock your tank with 10 of those small fish. If you choose larger specimens you would adjust your numbers accordingly. After you gain some experience at fish keeping, you can add more fish to bring the number over one inch per gallon, but it is still better to understock your aquarium than overstock it.