Fish Ponds

Add some fishy friends to your pond

While a garden pond full of aquatic plants is a beautiful addition to a backyard in itself, many people choose to add a little more life and activity to their pond with some fish.

Backyard fish ponds require a bit more care to set up and maintain than simple garden ponds, but the added value and beauty of fish ponds make it worth the trouble.

How to Build Fish Ponds

As with garden ponds, you have the choice between using a preformed fish pond and creating your own fish pond using just a pond liner. Preformed fish ponds are easier to install, but pond liners give you more control over the size and shape of your pond.

Size is particularly important when building a fish pond, because it will determine what type of fish and how many fish your pond can accommodate. Koi ponds should be as large as possible because koi will continue to grow despite the size of the pond. A length of at least 12 feet and a surface area of at least 140 square feet are recommended.

It is especially important to consider the depth of your fish pond. Deeper areas provide fish places to hide from predators, get out of direct sunlight and overwinter comfortably. Koi ponds should be at least 4 feet deep, and goldfish ponds should have a minimum depth of 3 feet.

Plants are essential to a fish pond ecosystem, but be careful which plants you chose for a koi pond, as koi will eat some plants. Goldfish, on the other hand, may nibble at vegetation but will not eat it.

Finally, don't forget to include rocks and hiding places in your pond. Fish are prey for birds, raccoons, cats and other animals, so they need a place to get out of sight.

How to Treat Algae in Fish Ponds

Algae are living organisms found in many aquatic environments. Although they are never a welcome sight in swimming pools, algae are actually beneficial to ponds. However, too much or certain types of algae are detrimental to your pond, not to mention unattractive.

To keep your pond's algae growth in check, limit the things algae requires to grow — namely, light and nutrients like nitrogen and phosphorous. You can do this by:

  • Locating your pond in partial shade or in areas of the yard that get limited amounts of direct sunlight
  • Covering part of the pond's surface with plants (40 to 70 percent is good)
  • Keeping only the number of fish the pond can support (about 1 6-inch fish for every 100 gallons of water)
  • Not overfeeding fish (fish waste contains the nutrients algae feeds on, and more food equals more waste)
  • Promptly removing dead plants and fish, as well as leaves, twigs and other organic matter that falls or gets blown into the pond
  • Adding scavengers such as snails, mussels and tadpoles to your pond; these remove waste produced by fish and plants, thereby inhibiting algae growth
  • Having a pond at least 3 feet deep to prevent sunlight from reaching the bottom
  • Using UV sterilizers and bio filters

Algaecides and other chemicals are also available for particularly bad outbreaks, but be careful, as these can harm plants and fish.

How to Clean Fish Ponds

Fish ponds should be cleaned once a year; any more than that can be damaging to the fish. Generally, the fall (before winterizing) or spring is the best time to clean your pond. Never clean a fish pond with soap or chemicals. Warm, fresh, de-chlorinated water is enough.

To clean your fish pond:

  1. Remove the fish into a tub or holding tank filled with a half-and-half mixture of pond water and fresh, de-chlorinated water; be sure to properly acclimate fish to prevent shock.
  2. Drain the pond as completely as possible.
  3. If you have potted aquatic plants, remove them to a shady area.
  4. If possible, remove statues, large rocks and fountains from the bottom of the pond.
  5. Clear the pond bottom of debris and silt.
  6. Using only fresh, de-chlorinated water and a soft brush, scrub the sides of the pond, as well as the rocks, statues and fountains you've removed.
  7. Rinse the pond filter (again, using only water – soap residue will harm fish).
  8. Pour half of the holding tank water back into the pond to re-introduce helpful bacteria.
  9. Refill the pond with de-chlorinated water and slowly acclimate the fish before returning them.
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