• A well-balanced goldfish pond provides adequate oxygen.goldfish image by Ahmed Zahir from Fotolia.com
  
  Enjoy the serenity of a traditional Oriental pond in your own backyard--the soothing sounds of running water, glimpses of goldfish gliding in the shadows. Chinese and Japanese nobility developed most of the goldfish varieties still being bred today, from fantails and veiltails to orandas and comets. Guard their health by offering enough space for adequate dissolved oxygen and "nutrient recycling," or waste decomposition--5 square feet of pond surface for every 1 to 6 inches of fish, conservatively.
  
  

Plants

• If your pond supports healthy plants, it will support goldfish. The right location helps: at least six hours of direct sun per day supports photosynthesis, which helps provide oxygen. But avoid direct mid-day sun, to keep water temperatures down, and also avoid locations directly under trees. Pools with an area 3 to 4 feet deep allow fish a place to retreat from summer heat and provide a winter survival zone for cold climates. Varying pond depths support many aquatic plant types; in a well-balanced pond plants rapidly remove fish wastes, which helps minimize algae overgrowth and keeps water clean and clear.
  
  

Pumps

• The amount of oxygen that will dissolve in water is miniscule. But water agitation "stirs" oxygen directly into water, which is why adding pump-driven waterfalls and other pumps support fish health. Fish get severely stressed at dissolved oxygen levels lower than three parts per million and will die if they drop much lower. Add an "air stone" or large aeration device to an air pump for more oxygen and to help lift and circulate water from the bottom. Circulating water also helps disperse wastes, moving them throughout the pond so underwater plants can use them as nutrients--then excrete oxygen underwater, as a byproduct of photosynthesis.
  
  

Filters

• Well-balanced fishponds may not need additional physical filters. But keeping ponds in balance can be challenging at times, so one or more mechanical filters are usually a good investment. The most practical types of filters for ponds are leaf skimmers, foam or sponge filters, and settling basins. Sponge filters are inexpensive, simple to service and easy to attach with an air stone or power head pump. Bacterial bio-filters are another low-maintenance option.
  
  

Deicer

• At least part of the pond needs to be kept ice-free so oxygen exchange can occur; if ice seals the pond for more than a few days the fish will suffocate. Goldfish will do quite well in winter otherwise, because at about 40 degrees F water becomes denser than either colder or warmer water, and that "puddle" sinks to the bottom of the pond, creating a safe zone for hibernation. Air bubblers and small water pumps are adequate where ice rarely forms, so long as water layers don't mix; disturbing the 40-degree water layer is fatal for fish. In colder areas, use a pond deicer to keep part of the pond ice-free. Deicers over 1,000 watts are better for climates where ponds freeze over for weeks at a time and are as energy efficient as low wattage deicers.