Keeping Goldfish and Koi Healthy– Pond Megastore

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Keeping Goldfish and Koi Healthy

Keeping Goldfish and Koi Healthy

Keeping Goldfish and Koi healthy is important to pond owners, fish breeders and dealers everywhere. We would like to give you some general information regarding how you can maintain healthy water quality for your fish, keep your fish healthy by recognizing diseases and parasites in your fish, as well as treatments for these diseases and parasites.

If you are a fish dealer or breeder, it is important that you quarantine your fish for 10 days. It is advisable to keep your holding facilities in the shade.

It is important that you use a test kit to monitor the levels in your pond.

Water Quality 

Water quality is one of the most important aspects of fish health. It is imperative that you provide your fish with the very best water conditions possible.

Biological Filters are an important part of good water quality. To understand how the Biological Filter Process works, you must understand the sequence of events which occur. When introducing fish into a new filter system,the filter really has no way to filter out the waste water. It is the addition of beneficial bacteria that actually filters out waste. Beneficial bacteria does all the work and is what actually removes the waste from the water. 

The use of a biological filter will help to ensure good water quality, but only when it is used in conjunction with a blend of beneficial bacteria. The beneficial bacteria, called Nitrosomonus, helps to remove fish waste from the water. Fish waste can cause a toxic level of ammonia in the water. Nitrosomonus will turn the ammonia into nitrite, another toxic chemical. Once the beneficial bacteria Nitrobactor begins to work, it will turn the nitrite into nitrates, which are basically harmless. 

Other corrections you can make at this time will be to feed your fish an absolute minimum, do 20% water changes and add 3-4 lbs of non iodized salt per 100 gallons of water. This will aid in reducing the toxicity of the nitrites.

Chlorine is often found in most tap water along with chloramines. They are used to disinfect the water supply. Chlorine dissipates within 24 hours but chloramines must be neutralized by using commercial water conditioners. Both chlorine and chloramines are harmful, as well as toxic, to fish. 

Fish are cold blooded  and tolerate temperatures from freezing at 32 degrees, to about 90 degrees. Fish need more oxygen in very warm water. When treating fish for disease, the water temperature should be between 65 and 85 degrees. Disease treatment is much more successful at these temperatures.

Aeration is important in a pond to provide oxygen for your fish. You can accomplish this by the use of air blowers, paddle aerators or air stones. Fish will come to the surface of the water and gasp for air when there is not enough oxygen in the water. When measuring for oxygen in the water, the levels should read 6ppm.

It is important to have pH levels of 7-9 in your pond, this is the measurement of hydrogen ions in the water. It will stress your fish to have levels lower than 7-9, if you find that your levels are too low, add one teaspoon of baking soda for every 10 gallons of water in your pond until your level increases. (Higher pH levels are acceptable, but the combination of high pH levels along with ammonia in the water will be deadly for your goldfish and koi)

Prevention for Ammonia Spikes in your pond are:

  • Test your water weekly for ammonia
  • Add beneficial bacteria
  • Remove debris such as sticks, leaves and other debris, their decay contributes to ammonia levels
  • Don't overfeed your fish
  • Use safe,chemical-free pond cleaners in your pond
  • Don't overstock your pond
  • Never do total water changes (you will be ridding the pond of all the good bacteria which is essential for a well balanced, healthy pond
 Too much ammonia in the water is deadly for fish. Ammonia comes from the uneaten food as well as fish waste in a pond. (Overfeeding your fish will cause this problem and is the Number 1 problem in most fish ponds) You really don't have to feed your fish at all, they will eat the naturally occurring algae in the pond. If you are not feeding your fish there will be no uneaten fish food creating ammonia, plus your fish will not be excreting more waste, which adds to the ammonia as well as algae issues we pond owners face.

Some indicators of ammonia poisoning:

  • Reduced slime coat
  • Damage to gills
  • Clamped fins 
  • Irregular movement 

The recommended ammonia level for your pond is 0 ppm. With regular pond maintenance and not overfeeding your fish, you should be able to maintain better ammonia levels in your pond.

If you find that your fish have ammonia poisoning, here are some suggestions to correct the problem:

  1. Once you test the water to see if the ammonia levels are too high, do a 20% water change. If the levels are still too high 24 hours later, do another 20% water change.
  2. Add ammonia remover to your water to detoxify the ammonia.
  3. Add beneficial bacteria to restore lost bacteria in the water change.
  4. Add Melafix if your fish are recovering from ammonia poisoning. Melafix will help your fish recover from sores and open wounds.
  5. Also add non-iodized salt to help restore the slime coat of your fish.
Through proper aeration, your pond will establish levels of oxygen. Dissolved oxygen is important and essential for your fish. Lack of aeration can kill your fish quickly, even in an established pond. 

    Oxygen deprivation symptoms in fish:

    • Reduction in appetite
    • Fish remaining near the surface of the water
    • Fish gasping for air

    If your pond lacks oxygen, you can:

    1. Add a waterfall or fountain
    2. Increase the Flow Rate by increasing the size of your pump
    3. Add spitters to help break the pond's surface  and increase the oxygen
    4. If your pond is deeper than four feet, use an airstone to supplement oxygen levels

      Some reasons your pond may be oxygen depleted are:

      • Warmer Temperatures, warmer water does not hold as much oxygen
      • Overpopulation of fish
      • Algae blooms
      • Aerobic bacteria

      Suggested oxygen levels are 7-9 mg/L of dissolved oxygen for healthy pond water


      Chlorine and Chloramines can cause fish death

      If you find that your fish are dying quickly with no real symptoms, the problem may be in your tap water.Tap water is safe for humans but may cause problems with your fish.

      Chlorine and Chloramine toxicity may cause:

      • Quick Fish death with no symptoms
      • Fish may gasp for air

      It is important to use a dechlorinator or water conditioner each time you add new water to your pond. The smallest amounts of chlorine or chloramines can kill your fish very quickly with no obvious symptoms. These chemicals attack your fish's gills and this prevents them from breathing. Chlorine dissipates within 24 hours but chloramines remain in the water and actually accumulates over time.

      A way to address these issues with chlorine and chloramines are to:

      1. Use a dechlorinator or water conditioner (folllow instructions and dosing recommendations)
      2. Use activated carbon


         Nitrite levels in your pond

        Maintain a healthy nitrite level in your pond by reducing the waste as well as encourage good bacteria to grow and add aeration with a fountain or waterfall.

        • Take care not to overfeed your fish 
        • Clean up any debris from nearby trees as organic matter discharges nitrogen into your pond water.
        • A biological filter will also help with high nitrogen levels.
        • Make sure to test your water if you see any signs of fish distress.
        • Adding salt along with a partial water change may help to bring down the nitrite levels.

          Your Nitrite level should be 0 ppm. Levels higher than 0.15 ppm can cause stress on your fish, making them susceptible to disease. You can reduce your nitrite levels by changing out 20% of your water, by adding beneficial bacteria to your filter and cutback on feeding your fish. Nitrite proliferation will kill your fish quickly.  Always make sure you are using fully cycled biofilters (filters with beneficial bacteria) in your pond.

           It is important to use test kits to monitor the levels in your pond. There is no way to know what your oxygen levels are, your ammonia levels, nitrite levels, etc. without a test kit.



          Bacterial Infections, Disease and Parasite

          Pathogens and bacteria as well as parasites are ever present in our ponds, when our fish are stressed they are more susceptible to these ailments. Before treating an illness or infection, be sure to correct any underlying conditions with the quality of the water in the pond. 

          Medicated food containing tetracycline has proven very effective for bacterial infections. Medicated fish food containing romet or oxolinic acid are also successful when treating bacterial infections. Feed fish medicated fish food for 10-14 days or as label indicates

          Anchorworms are a parasite that bear a resemblance to a small thread emerging from a scale on a fish. Ulcers often appear on the areas where the worms attach. Remember to keep your water temperatures between 65 and 85 degrees for the most effective treatment from your antibiotic treatment.

          Costia is a fish disease caused by protozoa, a small organism that attack the gills and skin on fish. Symptoms are an overabundance of slime production, rubbing their sides on the bottom of the pond, no appetite, and listlessness. Healthy fish in ponds with excellent water quality, rarely get Costia.

          Columnaris Disease is a bacterial infection with lesions resembling mold. White, mold-like tufts form on the mouth, fins and body of the fish. Columnaris affects fish that have been exposed to malnutrition, poor water quality or stress and is highly contagious. Treatment is with antibacterial medication.

          Carp Pox has a waxy, white appearance and is seen on koi in cooler water. It is nasty in appearance but is basically harmless. The condition is relieved when fish are in warmer water.

          Chilodonella is a microscopic parasite that affects fish in cooler water (40-50 degrees). Excess slime production, listlessness, lack of appetite and rubbing its body on the bottom of the pond are all symptoms of Chilodonella. Treatments include salt baths, salt dips, or Potassium Permanganate.

          Dropsy  is an infectious disease and could be symptomatic of a heart condition, kidney failure or an internal bacterial infection. Scales are often raised and eyes are bulging. Isolate Koi and treat with antibiotics. 

          Fish Lice appear as a small, dark area on the fish. It is fish lice that attach and make small holes in the fish, making the fish susceptible to bacterial infections. Treatment is with Dimilin.

          Flukes are the most prevalent parasite found on goldfish and koi fish. Large manifestations can cause excessive damage to fish and the symptoms include flashing, gasping for air at the surface, as well as frayed fins. Koi should be treated with Potassium Permanganate and goldfish should be treated with Praziquantel.

          Ich is a common disease in goldfish and koi. It is certainly the most widespread. Ich has distinctive, white spots the size of grains of sand. Symptoms include flashing, loss of appetite and lethargy. Treatment for Ich is salt for 10-21 days. Ich takes longer to clear in cold water.

          Ulcer Disease It is important to diagnose and treat Ulcer Disease early in its development. The indications for this disease are usually a red or white pimple that forms into a deep ulceration. The ulcer can proceed into the muscle of the fish. Make sure to place the affected fish in salt water and feed medicated food. Tricide Neo may also be used. Consult an experienced veterinarian if your fish is valuable as antibiotic injections may be necessary.

          Trichodina is another parasite that is recognizable by forming a gray film over the fish. The symptoms include flashing, lethargy and staying near the surface. Treatment includes a salt bath and Potassium Permanganate.

          Spring Viremia of Carp This disease is seen when temperatures are between 40-60 degrees and the temperatures are on the rise, always in the spring. This is a virus that is rarely seen in the USA. Symptoms can include hemorrhaging, darkening of the skin, raised scales, eyes bulging, and listlessness. This is a reportable disease and should be reported to the proper government authorities.

          Koi Herpes Virus is usually observed when water temperatures are between 70-80 degrees. This is an extremely contagious disease among koi that is often fatal.( Goldfish are unaffected by this disease) Major loss of fish can occur within a few days. Respiratory distress as well as gill necrosis is usually observed along with loss of coordination and hyperactivity. This virus is extremely hard to treat and there is no cure.


          Treatments For The Fish Diseases Listed

          Always treat you fish in water between 65-85 degrees. Fish treatments work better in these temperatures

          Always use Non-Iodized Salt when using any salt treatment 

          Salt Meters can be purchased at a reputable koi dealership or pond supply outlet

          Salt Dip 10 Tablespoons of salt per 1 Gallon of water   or   5 pounds of salt per 25 gallons Place fish in this solution for 60-90 seconds. Fish will seem distressed, turn white and turn upside down, but will quickly recover when placed back in fresh water

          Salt Bath 3 teaspoons per gallon of water   or   25 pounds of salt per 1,000 gallons of water  Place fish in this water for 48 hours


          Potassium Permanganate Treatment

           This is an effective treatment for many parasites. If you cannot positively identify the parasite, Potassium Permanganate should be your first treatment option. Follow dosing measurements carefully and complete a 25-50 % water change before you begin treatment. Add 1 level teaspoon of potassium per 800 gallons of water. Distribute the product evenly throughout the water by dissolving it in water beforehand. The water will turn pink or purple and then turn brown, depending on the amount of organics in the water. If these color changes occur in less than an hour, retreat the pond at 1/2 teaspoon per 800 gallons. You can monitor the color changes by placing a white cup in the water to measure color. Watch the color of the water closely for the next 10 hours and add more potassium each time the water turns brown. Once you have maintained the pink color for 10 hours. Do a 50% water change, adding dechlorinators to neutralize the potassium. and repeat dosing in 3-4 days. 

          Praziquantel is used for the treatment of flukes in both koi and goldfish and is quite successful.

          Dimlin is an effective treatment for anchor worms as well as fish lice.


          Fish Jumping

          There are many reasons fish jump, one reason is for the sheer joy of jumping! You will have to determine the reason fish are jumping by pulling out your trusty test kit and do some detective work. The following may cause your fish to jump:

          • High Ammonia levels
          • Chlorine or Chloramine toxicity
          • Low Oxygen levels
          • Unsuitable Nitrate levels
          • pH levels

          Fish may jump for reasons not associated with poor water quality. They may jump to avoid another predator in the pond (if your pond is overcrowded), a fish may jump to avoid an undesirable mate throughout the mating season or because of parasites, infections or disease.

          Once you are certain that the above mentioned stressors are not the cause, you can begin to seek a solution.

          Netting will not solve the reason your fish is jumping but may be able to keep your fish from leaving the pond.



          Most fish predators come from outside the pond. Predators like:

          • Heron
          • Cats
          • Raccoons

          Some solutions for the above predators are:

          • Netting
          • Decoys
          • Scarecrow


          Netting or a decoy may keep out heron. The decoy will have to be moved around the pond to keep a heron at bay.

          Cats and raccoons may be kept out of your pond with a scarecrow which emits a small spray of water at the intruder.

          One way to keep fish safe in the water is by providing plenty of cover inside the pond. Submersed plants, rockery as well as floating plants like water lilies, water lettuce and hyacinths give the fish cover from predators. Submersed oxygenators give fish and small fry cover from predators.

          Sometimes the predators come from inside the pond. Overcrowding with too many fish turns fish territorial and fish may attack each other. Large frogs will eat fish as well.

          There is a delicate balance we must achieve to keep our goldfish and koi healthy. Avoiding stress, disease, poor water quality and predators will help us achieve that healthy balance!















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