How to Maintain a Fish Pond

Proper maintenance of a fish pond involves far more than filling the pond with water, running it through a filter and introducing fish. Your outdoor pond may be the perfect spot for native frogs, salamanders and insects, such as mosquitoes, to breed. Algae may bloom and take over, dimming your view of your fish. Herons may see your pond as an expensive soup bowl.

Things You'll Need

  • Water chemistry test kit
  • Small floating ball
  • Fine-gauge black cotton thread
  • Small fountain pump
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Instructions

  1. Water Maintenance

    • 1

      Clean your filter's trap of debris often. This will increase the efficiency of your biological filter and reduce the possibility of developing an algae bloom.

    • 2

      Measure your pond water's pH, alkalinity, water hardness and nitrite levels prior to adding fish or plants, again after adding plants, and once a month after adding fish. You want these four measures to be in balance for healthy fish and plants. For a thorough study of how to maintain proper chemical balance, visit the website for the Koi Club of San Diego (see Resources).

    • 3

      Use only pH-balanced soil intended for potting water plants. Top potted plant soil with gravel to keep the fish from digging up the plants and stirring the dirt into the water.

    • 4

      Distribute fish food within a floating ring to keep it contained until the fish have eaten it. Watch the fish periodically to be sure all food is consumed within 5 to 10 minutes. If food is left, you are feeding too much. This can vary with the seasons and as the fish mature, so adjust the amount of food given as needed. In winter, once a day is adequate, as the fish are inactive. During warmer months, feed fish twice a day, in the morning and evening when temperatures are cooler.

    • 5

      Float a ball on top of the water to keep ice from forming solidly across the surface in winter. This will allow for gas exchange. Do not break ice by pounding on it---the shock will hurt the fish over-wintering at the bottom.

    • 6

      Drain the pond to just below a leak to repair it. If the leak is deeper than the fish will be able to swim comfortably, move your fish to a temporary pond while you make repairs. In a cement pond, using a vinyl liner material is more practical than attempting to fix the leak in the cement.

    Dealing with Frogs, Herons, Mosquitoes and Algae

    • 7

      Contact your local Fish and Wildlife office to find out how to dispose of bullfrog tadpoles. Bullfrogs will eat anything they can get into their mouths. Smaller frogs will most likely not pose a direct threat to your fish, but these animals will compete for space and nutrients with your fish and leave waste products behind, altering water chemistry.

    • 8

      String fine-gauge thread around the perimeter of your pond to trip Great Blue Herons before they can wade in and eat your fish.

    • 9

      Circulate the water in the pond to maintain constant temperatures. Mosquito larvae require warm, stagnant water and can usually be found in depths of 6 inches or less. Building your pond with steep sides and water at least 18 inches deep will help prevent mosquitoes from breeding in your pond. Underwater planters and overhanging leaves provide shelter for mosquito larvae. See links in Rreferences for more prevention and control tips.

    • 10

      Regulate the amount of direct sunlight the pond receives, either through initial location of the pond or use of surface floating plants. Direct sunlight is what algae need to thrive. Agitate the water with a waterfall or fountain at least every other day during warm months to oxygenate the water. Trim overhanging branches and plants to reduce material falling into the pond. Skim off leaves as they fall in. Reduce the number of fish in your pond and monitor the amount of leftover food. Clean the pond regularly just as you would an aquarium to reduce algae growing on the sides and bottom. In areas with good water flow and more sunlight than optimum, barley straw can reduce algae due to the chemicals it gives off as it breaks down. As a last resort, apply an algaecide as needed, found at fish and garden supply stores.