Caring for Pond Fish

  
 Types of Pond Fish

  Goldfish are the most popular fish stocked for water gardens.  They are active, hardy, and inexpensive.  Their colors range from black, white, and of course orange.  They may grow to lengths of 12 inches or larger, although 6-10” is typical in small water gardens around here.  Unusual body and fin shapes of goldfish occur, although they are not as hardy as the slender bodied, straight tailed common goldfish.  Goldfish will survive the winter in most ponds as long as they are at least 18” into the ground. Above ground ponds freeze solid so fish must be brought indoors under these circumstances. 

   Koi, meaning colored carp in Japanese, are larger fish growing to 30 inches or more.  They come in a greater array of colors and patterns, ranging from black, blue, white, yellow, reds and oranges.  Many times 3 or more of these colors can be found on one fish and unlike goldfish, these colors and patterns change throughout the koi’s life. A long-finned hybrid called a butterfly koi exists and is a little hardier than the standard koi.  Koi need at least 24” of water to do well in the winter, and even deeper water is recommended.

  Goldfish and koi can coexist in the same pond and will even cross breed.  The result is a multicolored fish called a shubunkin, or a calico goldfish.  It usually has black, orange, or red markings on a bluish background and large, dark colored eyes.  Transparent splotches are also common, especially on the gill covers.

 Preparing and Caring for Pond Fish
  In new ponds it is best to let the water sit for 3-5 days and let the temperature stabilize.  Tap water will require the addition of a chlorine and chloramines remover before the addition of fish.  Our tap water is a little hard and may require a pH test.  Older, established ponds typically have a balanced pH due to biological processes and should be fine.  A 6.5-7.5 reading is ideal, although fewer diseases and clearer water occur in a lower pH. 

  When adding fish, introduce only a few at a time as not to disrupt the bio-load of the pond. In a pond with standard filtration, add 1” of goldfish or ½” of koi per square foot of water surface to avoid overstocking. Overstocking leads to decreased water clarity and quality.  Keep in mind that fish grow and multiply readily.  Float the bag with the fish in the pond for 15-20 minutes before releasing it into the pond, so the fish may slowly adjust to the temperature. It
is best to keep the bag out of the sun to avoid overheating and undue stress.

  Since fall is a natural stress period for fish, it is also the best time to clean out the pond.  Leaving debris and sludge in the pond over winter can release toxic gases, which build up under ice and causes problems.  Making sure that just a small hole is always open allows these gases to escape.  A heater or a small pump placed below the freeze line aimed upward usually does the job.  Properly stocked and clean ponds may not have a problem at all.

 Feeding Fish
   If a pond contains a small quantity of fish, no feeding is really necessary.  Fish can forage on their own, eating
insects and algae.  Larger numbers may require supplemental feeding.  Goldfish and koi require high protein food
which are met by most flakes or pellets labeled for pond fish.  Higher quality foods have added protein and vitamins
which offer improved growth, color, and disease resistance.  When the water tempurature drops below 50 degrees,
pond fish shouldn’t be fed protein foods as it may rot in the intestines over the winter and cause problems. 
Occasional oatmeal or wheat germ food should be fed, if anything at all. 

  While goldfish are happy picking at the algae growing on the side of the pond, koi may take it upon themselves to
eat a little more vegetable matter.  Koi relish string algae, and koi ponds are typically free of it, as long as they are
not overfed with the food you supply them.  If koi are really hungry, they may nibble at your water plants and their
roots to supplement their diet.  Applying a layer of gravel that is larger than the koi’s mouth over the soil of your
water plants usually protects them from being uprooted. 

 Predators, Diseases, and Parasites
  The most frequent predators of ornamental fish around here are raccoons and herons.  They often have no trouble wading into a shallow pond and plucking out brightly colored fish.  Herons may deplete an entire pond of fish in one sitting.  The best defense for these predators is to build a pond too deep for them to wade into, usually a 2.5-3’ deep section is too deep for a blue heron to acess.  A pond with deep sides often discourages raccoons.  Submerged plants, rocks, or even clay pots allow fish a place to retreat when startled. 
 
  There are a number of diseases and parasites that may afflict pond fish, some fatal.  It is best to identify the
problem, or to have someone else identify it from where the fish was purchased before treating.  Fish stress, poor filtration and water quality often contribute to disease and parasite reproduction.  Adding one cup of uniodized salt per one hundred gallons of pond water helps cure many problems, while lowering nitrite toxicity and relaxing the fish.  Doubling the amount works even better, as long as no plants are present in your pond, as they may burn.