build a fish pond

You are here: Home > Pond Stocking

Pond Stocking

Pond Stocking is a delicate process and not something you do as soon as you have your pond up. Cycle your pond properly to make it safe for Koi and Pond fish. The time needed to cycle a pond successfully is a minimum of 4 weeks and can take up to 8 weeks.

New Pond Syndrome (NPS) is often the first and most expensive problem encountered by new pond keepers.

Because of the chlorine and chloramine in city water you have to use a dechlorinator to remove these. Letting your pond sit will not rid it of chloramine. Always keep a dechlorinator on hand for emergencies, and remember anytime you add water to your pond you must add your dechlorinator.

You may first encounter NPS unknowingly in the form of diseased fish in a new pond and hope that you will be able to medicate the problem away. Where NPS is the cause of the problem, treating fish is not the solution.

NPS is a term that describes what can happen if a new pond is stocked in haste. When pond stocking, if too many fish are added too soon, then more ammonia is released into the pond than can be broken down by the immature filter.

Remember: The time needed to cycle a pond successfully is a minimum of 4 weeks up to 8 weeks.

Ammonia poisoning causes damaged tissue, especially to the gills and kidney. It also causes physiological imbalances such as impaired growth, decreased resistance to disease. High levels of nitrite are also a problem. Nitrite poisoning inhibits the uptake of oxygen by red blood cells. Known as “Brown Blood Disease,” or Methemoglobinemia, the hemoglobin in red blood cells is converted to methemoglobin.

In the wild, both in and out of water, organic waste materials of all sorts (dead animals and plants) break down into ammonia. Both ammonia and nitrite are highly toxic to fish. By testing the water regularly and keeping on top of any ammonia or nitrite issues, you can prevent this serious health implication.

To avoid NPS you need to use Jump Start to help cycle your pond.

Symptoms of NPS

If your pond is less than three months old, the symptoms of NPS can be recognized as follows:
  • High ammonia
  • High nitrite readings
  • Fish gasping
  • Sulking
  • Swimming erratically
  • Not eating

When beginning your pond stocking, test your pond water frequently for PH to ensure that you maintain it at the correct level. You should also test ammonia and nitrite regularly during the running of a new pond. These tests will show how the filter is maturing and whether it is keeping pace with the rate at which waste is produced.

The pond temperature must be 60° F or above for the beneficial bacteria to multiply.

If the PH is too high, carry out a partial water change with soft, acidic water, and check for sources of buffer in your pond that could be raising the PH to extreme levels. If the PH is too low, add some tap water or add a source of lime such as limestone chipping or crushed shells.

When first filling your pond this is a perfect time to find out the Volume of your Pond. Using a water meter attached to a hose when filling your pond will accomplish this. Don't forget to set a timer too.

In nature, fish stocking levels are much lower than in our artificial environments. When stocking levels become too high, fish populations are brought under control by predation, diseases, stunted growth or other mass die-offs. In our artificial environments, we often forget that stocking levels are important, and just as in nature, there will be a tendency for equilibrium to become established over time. Unfortunately for our pet fish, "equilibrium" usually means disease or death. Eliminating excess fish stock brings the environment into a state of equilibrium. A minimum of 100 to 200 gallons per fish is adequate. If you want to raise jumbo Koi (30 inches and larger), a stocking density of 1,000 gallons per fish may be required.

Resources: Ponds & Water Gardens

The Basic Pond Nitrogen Cycle

The purpose of your filtration system is to provide a beneficial bacteria farm that will consume fish waste, uneaten food and decomposed matter before it turns into deadly ammonia. Fish and Pond keeping means monitoring your pond or water feature for ammonia.

A new waterfall biofilter with pads or brushes, or an external filter installation will start to develop beneficial bacteria in a few weeks naturally. However it can take a few months to fully develop its own bacteria farm. During this break in time ammonia levels may fluctuate dramatically.

Perform partial water changes if ammonia levels rise above 1.5 PPM to reduce toxic ammonia levels. Once your filtration system has an active bacteria farm it will be able to handle normal pond waste byproducts.

Experienced ponders use commercially grown bacteria and add it to their ponds at the start of each season and seed it throughout the year to insure there is plenty of bacteria to consume the waste.

~Important Points to Remember When Pond Stocking~

FISH WASTE: Fish produce urine and excreta. Waste is also present in the form of uneaten food and pieces of decaying plant fragments. Leaves, grass clippings, pollen and molds may also be present in varying quantities. Animal matter may be present in a wide variety such as dead insects, bird droppings and thousands of other situations. Anything that falls into your pond will decay if it is plant or animal. It is important to check your pond periodically for anything that has fallen into the water and remove it before it overwhelms the pond filter and produces deadly ammonia.

DECOMPOSED WASTE: This matter is attacked and changed into ammonia by heterotrophic bacteria. World-wide outside of aquaculture as well, any living organism that dies is transformed by bacteria into particulate matter and ammonia is a byproduct of this naturally occurring event.

AMMONIA: Ammonia is a highly toxic substance to fish. It is present when first starting a pond or water feature up and cannot be avoided. New aquaculture installations must go through a rising ammonia cycle. New installations should be planted with fish that are not valuable in case you cannot manage the cycle properly. You can purchase large cheap goldfish (4"-5") for around a $3.00 each and use them to cycle your pond if you don't mind having to spend a few hours chasing them down with a net when the cycle is complete. Don't use small feeder goldfish as they may hide in the cracks of your pond rocks and die, causing an ammonia spike.

NITRITES: Nitrifying bacteria change the ammonia into nitrites.

NITRATES: are not as toxic as nitrites; they act as food for plants and algae in the pond. Nitrate is produced by one of the autotrophic bacterial colonies by combining oxygen and nitrite.

PLANTS: Plants absorb and metabolize most of the nitrates as a food source. The excess nitrates that your pond plants do not eat is left in your pond and algae forms to eat it. Algae outbreaks are a sign that you may have too many fish, you are overfeeding your fish, or you don't have enough pond plants to consume it.

PARTIAL OXYGEN RETURN: Oxygen is returned to the water from your pond plants. This amount of oxygen is not enough to depend on as a viable source. Plants produce oxygen in the daylight hours and consume oxygen in darkness. Having plants in your pond is a huge plus. Plants control algae outbreaks by using the excess nutrients in the water, plus they look beautiful.

Ammonia Readings for Pond Stocking

The desired ammonia reading is zero; if you have a positive reading (which suggest that the ammonia excreted by fish is not being broken down), you should stop feeding the fish immediately.

Do not introduce any new fish or feed your fish until the reading is back to zero.

For the next week take a reading every day to make sure it is at the right level.

Nitrite Readings for Pond Stocking

The only desirable nitrite reading is zero, and if a positive nitrite reading is present, it is an indication that the filter is not coping with the amount of waste. Even a low nitrite reading is undesirable.

Nitrifying bacteria are classified as obligate chemo-lithotrophs. This simply means that they must use inorganic salts as an energy source, and generally cannot utilize organic materials. They must oxidize ammonia and nitrites for their energy, and fix inorganic carbon dioxide (CO2) to fulfill their carbon requirements. They are largely non-motile and must colonize surfaces such as gravel, sand or synthetic bio-media, for optimum growth. They secrete a sticky, slime matrix, which they use to attach themselves.

The two most common species of Nitrifying bacteria, mentioned above, are Nitrosomonas and Nitrobacter. They are gram negative bacteria, ranging between 0.6 and 4.0 microns in length. They are obligate aerobes and cannot reproduce or convert ammonia or nitrites without oxygen.

Nitrosomonas utilize ammonia (NH3) as an energy source during its conversion to nitrite (NO2). Ammonia is first converted (hydrolyzed) to an amine (NH2) compound then oxidized to nitrite. Nitrobacter use nitrites for their energy source during its conversion to nitrate (NO3).

Most of the energy produced by Nitrosomonas (up to 80%), is devoted to fixing CO2 and little energy remains for their growth and reproduction. As a consequence, they have a very slow reproductive rate. Because little energy is produced from these reactions, Nitrosomonas have evolved to become extremely efficient at converting ammonia and nitrite. Scientific studies have shown that Nitrosomonas are so efficient, that a single Nitrosomonas cell can convert the same amount of ammonia as approximate 1,000,000 heterotrophic bacteria (standard pond bacteria).

The water temperature for optimum growth of Nitrifying bacteria is approximately 75 – 85°F. Growth rate is cut to 50% at approximately 65°F, and cut by 75% at approximately 50°F. Growth is zero at approximately 40°F or below. Nitrifying bacteria will die if frozen, or if water temperature reaches 120°F.

Before adding bacteria to a pond or aquarium, all chlorine and chloramine must be completely neutralized. Most US cities treat their drinking water with chloramines. Chloramines are more stable than chlorine. The type of chloramines formed is dependent on pH. Most chloramines exist as either monochloramine (NH2Cl) or dichloramine (NHCl2). These com-pounds are created by adding ammonia to chlorinated water. Commercial chlorine reducing chemicals, such as sodium thiosulfate, will break the chlorine: ammonia bond. Chlorine (Cl) is reduced to harmless chloride (Cl-) ion. Each molecule of chloramine that is reduced, will produce one molecule of ammonia. When treating, first neutralize all chlorine. Then eliminate ammonia.

For Help In Keeping Your Pond Water Stabilized Click Here.

Prevention of NPS

The most reliable method of preventing NPS is to stock your pond wisely and patiently. Add Koi & Pond fish gradually over the first 3 months of a new ponds life and monitor the ammonia and nitrite levels.

After stocking your pond with Koi watch your fish during this time and look for any signs of stress (if you don't know what stress in your Koi looks like click here for the Koi Health and Wellness Center. You can help the maturation of your new pond and filter system by adding a source of bacteria.

Properly cared for, your fish and it's offspring will reward you with many hours of enjoyment. Treat them as kindly as you would any family pet.

Average Weight and Length by Age

When pond stocking remember to plan for the future. Overcrowding of Koi and Pond Fish is one of the main causes of Stress for your Koi.

Age (Years) Length (cm/in) Weight (g/oz)
<1 6(15) 2(60)
<1 7(18) 4(120
<1 8(20) 7(210)
<1 10(25) 12(350)
1-2 12(30) 20(550)
1-2 16(40) 40(110)
2-3 20(50) 80(2,200)
2-3 24(60) 160(4,500)
3-5 28(70) 390(11,000)

Other factors to keep in mind when trying to find your stocking level is:

  1. Type of filter system
  2. Aeration in the water
  3. The pond keeper's ability at detecting Koi disease or stress.

A good stocking guideline is no more then one Koi per 200 gallons.

The more room your Koi have they more they can maintain good coloration, they won't have as many disese problems, and you can maintain a higher quality fish.

Disease can spread very quicly in a crowded pond.

Fill out the form below and you will immediately receive a free 10 page ebook about your Water Quality



Don't worry -- your e-mail address is totally secure.

We hate spam as much as you do! Your name and email address will NEVER be sold, shared, or disclosed.

PLUS: * Koi Times Ezine--A free subscription to our newsletter which is filled with Koi, Pond, and Plant Tips, periodically delivered directly to your email in box.

"The latest newsletter came perfectly timed! Thanks for reading my mind and sending this material our way. A big help!" Terri

Koi Pond Blog | Build a Koi Pond Homepage | Pond Algae Control | Koi Health & Wellness Center | Koi Fish for Sale

koi pond picture

Share |

Pond Starter Kit

Koi Pond Starter Kit

~Price $92.99

S.A.F.E. Koi pond limits

S = stocking levels limited to no less than 10 gallons of water for every inch of fish in the pond-the length of a fish is calculated by the tip of their nose to the tip of their tail. Note: this calculation needs to be revisited if and when significant growth occurs in the Koi, i.e., when fish grow, you need more water.

A = aeration levels limited to no less that 80% of full saturation dissolved oxygen levels.

F = flow rate through bio-converter should be no less than 60 gpm (gallons per minute) for each pound of food fed to the fish each day. This minimum flow rate is scaled up or down in direct proportion to the feeding rate.

E = emergency capacity for life support when other things fail. This is equal to double the pond volume after all minimum conditions above are met.

E stands for emergency, meaning that even though the stocking (S) levels, aeration (A) and flow (F) through the bio-converter are adequate, there is some likelihood they will either functionally fail or fail to perform as expected. At that point an emergency situation exists until systems can be returned to a safe status where the lives and health of the fish are not in danger. The extra volume of water mitigates (not prevents) that emergency. The fish will have a greater chance of survival in the larger volume of water and the oxygen it holds. The SAFE formula requires pond owners to have double the amount of water needed to meet minimum requirements of “S,” i.e., safe stocking levels.

The S.A.F.E. Koi pond limits was founded by K.O.I. Koi Organisation International.

Enjoy This Site? Then why not use the button below, to add us to your favorite bookmarking service?

Koi Pond Blog
RSS Feeds

Twitter Button

Pond Stocking Beginning

You are here: Home > Pond Stocking

Contact Us

PayPal Acceptance Mark

Return to top
Copyright© 2008-2020.Koi-Pond-Guide.com