feeding koi fish

Koi Fish ~ The “Living-Jewels” of a Water Feature

Koi fish are prized for their unique colors and ornamental markings. Worldwide, the popularity of keeping “living gems,” such as koi, has increased over the past two decades. They are growing to be a global phenomenon, with clubs, shows, magazines, and so forth. Obsession is a typical result of the hobby of keeping koi.

There are many ways to care for koi. Although it may seem overwhelming at first, your understanding and knowledge will grow. These magnificent fish will soon grow to love. You will be hooked.

This guide is for everyone, from the most enthusiastic to the least. Beginners to koi-kichi (koi crazy). Aiming to reflect current thinking and the most recent technological advancements. Equipment and keeping methods. Including koi fish foods, pumps, filtration systems, and all manners of products available.


history of koi

Carp are a family of fish initially found in Central Europe, Asia. Many carp species were first domesticated in East Asia as food. Carp are coldwater fish and can adapt to different climates and water conditions. Domesticated carp species were able to be propagated to new places, including Japan. All populations would have experienced natural color mutations of these carp. Texts from the Jin Dynasty (4th century AD) mentioned carp of different colors. The Japanese history book Nihon Shoki, published in 720, is Japan’s oldest reference to colored carp. According to the Nihon Shoki, Emperor Keiko was said to have praised colored carp found in Mino in 94. Emperor Suiko also saw them in Soga No Umako’s garden in 620. Carp was first domesticated in China over a thousand years ago for color mutations. This was also where the creation of the Carassius auratus (goldfish) took place.

Cyprinus rubrofuscus, also known as the Amur carp, is a complex cyprinid species native to East Asia. Although the Amur carp was initially identified as a subspecies (C.c. haematopterus), recent authorities have recognized it as an independent species under C.rubrofuscus. Since at least the fifth century BC, Amur carp has been aquacultured in China as a food fish. In Japan, the systematic breeding of ornamental Amur Carp began in the 1820s in Ojiya (located on Japan’s northeastern coast of Honshu) and Yamakoshi (in Yamakoshi). Red carp, pale blue Asagi, and white, yellow, and red Bekkou were first developed through selective breeding. Around 1830, the Sarasa variety was designed with a red-on-white pattern. A yellow-based Ki Uturi variety was later created. All other Nishikigoi varieties except Ogon (single-colored and metallic koi) were bred from the original few koi varieties.

The development of color variations within Japanese koi was not known to the outside until 1914, when the Niigata Koi were displayed at an annual Tokyo exposition. Interest in koi grew throughout Japan. As the variety of koi fish grew, so did the number. Recurrent cross-breeding produced more attractive types like Kohaku, Taisho Sanshoku, and Showa Sanshoku.

The majority of koi were brownish-colored and did not have specific colors. Niigata, located on the Japan Sea, has been a significant prefecture for rice production. It is also well-known for its seafood, hot springs, and ski-ways.

What is the relationship between rice farming and koi fish?

Many rice paddies offered the possibility to raise koi fish as an additional source of protein for winter. The koi were placed in rice paddies that had plenty of water. The koi fish fertilize rice plants with their droppings. However, rice plants filter out and absorb nutrients from the droppings. This cycle continued into winter when farmers harvested the Koi to provide extra protein and help their families through the winter.

This is very similar to modern aquaponics, which frequently includes koi.

Enjoying Koi Today

The 1960s saw a boom in koi-keeping when almost everyone in Japan kept koi. Today, there are only about 1,000 koi-breeders. Koi that originated mainly in Japan are now being bred all over the globe, including Thailand and South Africa. Japan has been known to improve the quality of its koi. It now sells and specializes in the high-quality, premium koi that we have come to expect from Japan. The Zen Nippon Airinkai (or ZNA), the largest koi society in the world, provides excellent support for Japanese hobbyists. It is now available online. Many countries have koi-keeping clubs run by passionate volunteers who want to share their knowledge with new members. There is a wide variety of koi magazines all over the globe.

Koi can be purchased in many local pet shops. Specialist dealers have higher-quality fish. The pursuit of collecting koi is now a social one. Hobbyists passionate about koi join clubs to share their knowledge and assist each other with their koi. Notably, the high-quality carp had seen a rise in price since the 21st Century, when wealthy Chinese bought large amounts of koi from Niigata, Japan. A Chinese collector purchased one carp in 2018 for $2 million. This is the highest ever price. Some carp purchased in China are sold abroad and bred there. Although, many breeds are expanding worldwide.


Meaning & What Koi Fish Symbolize

Origin of the Name Koi

Koi can be described as flower carp, brocaded carp, fancy carp (nishikigoi), or colored and colorful carp. They are now known as koi carp. They were initially called Hirogoi (or Irogoi) in Japan. Later, they became known as just goi or koi. Nishikigoi is the Japanese name for single and multicolored carp. The term “koi,” which refers to a wild carp, was first used to describe it by King Shoko of Ro to Confucius at his first son’s birth.

The Japanese term for carp is “koi,” later used to refer to all carp, including the wild and more recent colored varieties. It is not clear from documentary evidence that the term “koi,” which was initially used to describe modern-day colored carp, was ever first used. Many names have been given to colored carp over the years. Colored koi were initially exported to the West mainly in red or red-and-white.

The Japanese term nishikigoi was used to describe a costly cloth made from many colors from India. It was imported into China and Japan by the Indian subcontinent. Nishikigoi is a “carp of many colors.” Nishikigoi is considered to be the Japanese national fish.

What do Koi Symbolize?

In Japan, koi symbolizes many good qualities. Koi swim against the current, overcome significant obstacles, and symbolize strength, perseverance, patience, strength, and courage. Koi symbolize prosperity and luck because they can live long and grow large. They symbolize peace and tranquility because they move slowly and gracefully.

Koi are likely to be found in Japanese gardens with a koi pond- near or within temples or palaces. These are also auspicious locations that kept koi for their visitors’ benefit—ensuring luck and success.

Koi & Japanese Proverbs

Numerous sayings Japanese proverbs mention koi fish. Two of these common ones are listed below.

Koi No Takinobori – A koi swimming up a waterfall.

Oyobanu koi no takinobori- a koi who cannot swim to the waterfall. This refers to an impossible situation where effort, passion, or dedication are not enough to achieve something. This saying is often based on “koi,” which in Japanese also means love. It can also refer to unrequited affection.

Koi Personality

Koi are peaceful fish and interact with other fish in their school but not with those outside their school. They swim in beautifully coordinated groups of 5 to 15 fish and form schools.

Koi will visit all levels of your pond. Swimming along the surface and the middle water depths searching for natural food at the bottom. They will seek shelter in deeper parts of the pond when it is colder. But, they are active, free-swimming, and will display their vibrant colors whenever they get the chance.

The hunting method for koi fish is unique. When foraging, they will dig into the sediment and eat any tasty seeds they find. They eat like a vacuum and take in large sips of food while filtering out dirt and mud.  They use the teeth in the back of their throat to grind up the food.  Yes, you read that right- koi fish do have teeth.

They are a significant pest to freshwater ecosystems because of their unusual feeding strategies. That competes with other native fish species.

Different Types of Koi Fish

Koi can grow to lengths up to 3 feet. They are the largest cyprinids and the most common fish kept in backyard ponds. They have two barbels on either side of their jaws and around the nose. Females have larger bodies and are rounder than males. Their fins are typically short and round with lobed caudal fins. Some varieties, however, are bred to have long-trailing fins.

These stunning fish are available in striking colors. Usually white or silver with iridescent scales, colorful spots, and markings. The markings may be red, gold, orange, and even deep blue. The type determines the exact color and markings.

swimming koi fish

Butterfly Koi Fish

Butterfly Koi, also known as Dragon Koi, are named for their long caudal and pectoral fins. Keepers are highly regarded, and they are precious.

You can find this variety in all the usual color forms. Its fins’ length distinguishes it.

Japanese Koi Fish

These are the most common Koi you’ll see in most ponds or water gardens.

Kohaku Japanese Koi have orange/red markings. They are the standard variety.

Tancho Koi is a Kohaku Koi with a single red spot at the top of their heads.

Dragon Koi Fish

Two types of Koi can be called dragons. It’s more often used to refer to the Butterfly Koi. 

Kumonryu is also known as a Dragon Fish. This fish is black and white with markings that vary according to the season.

Black and White Koi Fish

Shiro Utsui is white Shiro Utsui fish with black markings and spots. Some fish have a split-head design with white on one and black on the opposite side.

Matsuba Koi can come in black or white and black with gold markings.

Gold Koi

Ogon is a prized, one-color variety. Ogon fish can be either entirely silver, gold, or orange.

Ki is a typical koi name with gold markings on white bodies. Kinrin fish sparkle like gold coins and have beautiful scales.


Habitat & Conditions

Koi fish have evolved by dealing with the conditions in rivers and lakes.  Because they are large, lakes and rivers can have stable ecosystems. It is rare for significant fluctuations in concentrations to occur and, if they do, it is a slow process that gives the koi a chance to adapt. But, conditions can rapidly change in a pond, leading to death or destruction.

Fluids that are near one another are more likely to mix. Although a membrane can separate the Koi’s watery environment and the Koi from it, it does not stop “what is in water is also found in Koi!” Diffusion allows for positive influences on the koi’s internal fluids, which are sensitive to external forces.

  • You change the koi when you change the environment.
  • The more extensive the pond and the better its ability to absorb change, the more stable it is.
  • Fish can’t adapt to significant environmental changes in controlled environments. Changes should be minimal.

This is the essence of koi-keeping. Habitats that are predictable, consistent, stable, and predictable.

What Size of Koi Pond?

Koi require at least 250 gallons of water per fish. A school of large koi may need up to 1,000 gallons- as they require 10 gallons of water per inch.

A pond should be at least 5-6 feet deep and contain shallow and deeper areas.

Taking Care of Koi Fish

koi pond

Feeding Koi

Koi belong to the carp family, but they eat like vacuums. When they are most active, it is crucial to give them as much food as needed. When temperatures are above 60 degrees, it is essential to ensure that they are fed the proper diet. Beautiful and healthy fish must have the correct protein/amino acids, fat, and fiber ratios.

Below is a chart that shows the ideal percentages to achieve optimal growth and color. These percentages were created by Aquatic Nutrition (AQN experts) and have proven effective for many years.

Cool Season/ Wheat Germ
Max Grow
Amino Acid / Protein 32%40%38%38%

Koi also eat plants, seeds, plant material, alga, zooplankton, and insects. They don’t prey on fish, but they may eat eggs from other fish. The best diet for them is a mix of natural and commercial koi food.

They will eat aquatic plants and algae. Keep plants protected with plastic pond plant baskets to discourage koi from destroying your plants.

Introduce brine shrimp and water fleas to your pond to satisfy their love for zooplankton. You can also offer them insect larvae.

You should give them high-protein commercial food. Pellets can reach all depths but usually float on the surface. They can also be supplemented with rice and corn from the farm.

Learn how you feed koi fish by hand.

How Much Food is Enough

When koi are one year old or younger, they will usually eat 5-10% of their body weight daily. Fish three years old and older generally consume about 2% of their body weight daily.  This is about 20 grams of food per day.

Feed once a day when temperatures are between 50-59 F degrees.  Once above 68 F, provide twice a day.

Avoid excess food by only giving them an amount to eat within 2-3 minutes. Extra food is not digested well and can cause pond water problems.

Water Quality

These are the water quality metrics you should be looking at for healthy fish.
Low concentrations of ammonia (0.15 ppm, 0.15 mg/liter) are the most dangerous and can cause death. An active biologic filter will reduce ammonia levels to below0.1 mg/liter in a pond. Acceptable level = 0.

If you have Nitrite levels above 0.1 mg/l, it is recommended that you do a partial water change according to your test results. Acceptable level = 0

If nitrate levels are higher than 20 mg/l, you must change partial water or add AmQuell+(c) to the solution. The ideal level is below 60 ppm, but it is better to be closer than that.

PH is the ratio of Hydrogen ions (acidic) to Hydroxyl ions. It can be measured on a logarithmic scale ranging from 0 (pure acids) to 14 (pure Alkaline). Pure water is 7.0. This means that it has the same hydrogen ions as hydroxyl ions. The majority of tap water is between 7.4 and 7.6, ideal for Koi as they thrive in water temperatures between 7.2 and 8.0. Koi can tolerate a wide range of PH levels, from 6.5-9.0 to 0.2 per hour. However, they cannot make rapid changes in their pH. Happy koi can tolerate 7.4 to 8.4.

Pond owners often view temperatures as more than just a concern for their Koi. You should monitor water temperature for seasonal swings as well as daily fluctuations.

Temperature can affect dissolved oxygen levels and respiration and metabolic rate, pH balances, dissolved ammonia/ionized nitrogen ratios, and osmoregulation. Koi can tolerate temperatures up to 90 degrees F. They can also tolerate ponds that have been iced. Your fish may become stressed if the temperature of your pond changes more than 4 degrees F. an hour. A waterfall or shading can help reduce temperature fluctuations. A 0.1% sea salt solution with Calcium, potassium, and sodium will help reduce stress in a pond exposed to extreme temperature changes. You should not help if you did not alter the pond’s temperature, as with pH. Slowly. Koi will tolerate low-to-high temp changes better than significant top-down changes.

Water Hardness consists of permanent or general hardness and carbonate/bicarbonate hardness. Because of the relationship between salt in their bodies and the dissolved salts found in the pond, Koi perform better in hard water. Salt concentrations are different in soft water, so the koi must work harder to stop the salts from escaping their gill membranes. The koi can adjust their osmoregulation to cope with more challenging water, which helps reduce stress.

Bicarbonate ions buffer the water and reduce minimize the PH shifts. This is another reason for stress in Koi. The carbonate hardness required for Koi is between 150 and 300 mg/liter, or 9-18 degrees dH. The water in most Koi ponds is too soft, as there is no natural mud bottom that leaches minerals into it. The hardness of the water is increased by sodium bicarbonate and marine salt. Koi can benefit from a permanent salt solution of 0.1%. This works out to eight pounds per 1000 gallons. If you add salt to your aquarium, ensure that your pH is correct. Salt cannot evaporate and must be replaced if the water has been drained.

Because it is linked to water temperature and algae, dissolved oxygen is typically only a concern in warm weather. The oxygen requirement of large fish is higher than the oxygen supply. Low oxygen levels can stress and kill the largest fish. As your fish become more prominent, safe ponds could become less secure.

The water’s ability to retain dissolved oxygen is more remarkable the colder it is. Algae absorb oxygen at night and can cause suffocation for large fish. They also inhibit the oxidation of nitrifying bacteria. Dying algae and organic matter also take up oxygen. You can test for dissolved oxygen to determine if the water has enough. A fountain or waterfall can be used to aerate the water. Venturi valves on air compressors and typical pond aerators are also excellent for oxygenation.

If your water source is not from a well, you should test for chlorine and chloramine. While chlorine will go away on its own in about a day, chloramine must first be chemically broken down. Your local water agency can help you determine if chlorine or chloramine is added to your water. These chemicals can damage the liver and gills, and even low levels can lead to stress that eventually leads to illness. They are also added to water supplies to kill bacteria. Chloramine or chlorine can kill beneficial, nitrifying bacteria from your biological. These chemicals are safe for your fish and cause no visible damage.

Copper should be tested if water is supplied via copper pipes or if coins are placed in the pond. Copper will not leach into harder wastewater than water in its purest form.

A thorough pond cleaning is the third thing that you should do. Clear out any debris (e.g., dead leaves or settled solids) from the bottom of your pond. Clean out your pond filters.

The next step is to do a 40 – 50 percent water change. Use a de-chlorinator such as AmQuell + if you live in a city. This product can remove/detoxify all types of toxic nitrogen compounds from your water. It will also remove all ammonia, ammonium, and nitrites from the water.

Let’s say that your pond water tests out to be within the normal range, but your fish still show signs of illness after a few days. If this is the case, you should isolate the fish or fishes from your pond and place them in a separate holding tank with good water quality. The Isolation Tank should be “salted.”

It is essential to perform water changes regularly according to one of these schedules:

  • Every week, 10%
  • 20% every two weeks
  • Every three weeks, 30%

These criteria are crucial to setting up your water exchange schedule.

Outdoor ponds are not subject to any set of rules. The “fish load,” which is the number of fish you can keep in an outdoor pond, depends on how big the pond is, what type of filter it has, the size and capacity of the pump. It should also “turn over” all the water within the hour. Water quality must also be considered. Keep in mind that the more prominent fish, the more waste they produce. Make sure your pond filters can handle this!

Water exchange is achieved by pumping out water according to the size of your pond, fish load, schedule, and other factors. You can then “spritz” the water into your pond slowly to dissipate most of the chlorine.

You will need a de-chlorinator such as AmQuell + if you live in a city. This product can remove/detoxify all types of toxic nitrogen compounds from your water. It will also remove all forms of ammonia, ammonium, and nitrites from your water, including the ammonia found in chloramines.

Keep in mind koi ponds are closed eco-systems. There are no freshwater sources other than rain and water that you have put in. Even with a moderate fish population, freshwater doesn’t last long.

Inadequate pond water maintenance can lead to a buildup of compounds such as phosphates, proteins, and other harmful substances that inhibit Koi’s growth and health. Water changes are essential to replenish water minerals and trace elements, which minerals and trace elements that koi fish require to achieve their full potential.

The most important environmental factor in maintaining healthy fish is water quality. It is also the easiest thing to maintain. If it is not kept, your precious Koi, Butterfly Koi, and Goldfish may exhibit stress-related behaviors that make them look sick.

The water quality should be compatible with the needs of the fish being kept, including ammonia, nitrogen, nitrate, pH, and temperature. While the initial water quality of a system is determined by its water source and treatment methods, long-term water quality in a circulatory system is affected by many factors. The main primary considerations in a design are the water source, fish load, feeding rate, and biofilter capability.

Before establishing a system, an Aquaculture specialist and a laboratory for water testing should assess the water source. Other potential problems may exist in water from different sources that need to be addressed. Water from municipal sources could contain chlorine or chloramines. Well, water may also contain hydrogen sulfide, supersaturated gas (such as nitrogen gas), high carbon dioxide levels, along with low oxygen levels or high dissolved iron (all conditions that can prove fatal to fish); surface water sources might be contaminated with bacteria or toxic chemicals due to runoff.

Toxic ammonia and nitrite levels are the most frequent water quality problems in recirculating systems. This is due to imbalances between the biofilter’s capacity and fish load and feeding rates. Although this problem is most common during system startup, it can also occur anytime. It can take the bacteria in the biofilter three to eight weeks to cycle (i.e., become established) at 25 to 27 degrees Celsius (77 to 81 degF). More time will be required (see UF/IFAS Fact sheet FA-16 Ammonia). AquaculturistsAquaculturists often initiate this cycling process usually start this cycling process beforeprocessbefore the process bit before adding fish using one of these methods.

Ammonia can be added directly to the system.
You can add a fish species that are more tolerant to the initial high levels of ammonia or nitrite before adding the last species. However, this presumes that the fish have been tested for any potential pathogens they might bring to the system.
SeedingI is seeding the biofilter system/biofilter using bacteria from an established, healthy system or commercially reputable source.

Overfeeding, crowding, or inefficiently removing solids (such as fas feces and uneaten foods) can lead to toxic levels of ammonia. This will cause the ammonia to be broken down into large proteins in established filters. Problems caused by ammonia and nitrite, problems due to source water issues (desc, ribbed above), and difficulties due to source water issues (described above) can also be caused by changes in water quality parameters. The following parameters can change in a system over time: dissolved oxygen (DO), decreases, alkalinity(decreases), carbon dioxide (“can increase”), and pH (drops).

Many factors can lead to low DO in a system’s operation. These include inadequate water flow, low water quality, poor aeration, excessive stocking density, insufficient water flow, insufficient aeration, large organic loads that can lead to high levels of bacteria, and those found in the biofilter. Systems with minor water loss or slight or adding water frequently experience gradual pH drops due to gradual acidic addition and alkalinity decrease.

As a result of nitrification, bacteria in the biofilter produce acid (H+), which is a process that transforms toxic ammonia into nitrite and nitrate into a much more toxic form. The water is then enriched with Hydrogen ions (H+), as ammonia becomes nitrate and nitrate becomes nitrate. The acid reacts with the bicarbonates and carbonates to use up the carbonates, reducing alkalinity. Drops in alkalinity can also cause ammonia and Nitrite spikes. The biofilter bacteria require the bicarbonate component of alkalinity to survive and grow.

Acids can also be formed from the breakdown of fish wastes, uneaten foods, and carbon dioxide released by bacteria and fish in the water. These acid additions react to the bicarbonates or carbonates in the water, causing alkaline drops. Alkalinity is essential for biofiltration and as a buffer pH.

As mentioned above, alkalinity components (especially carbonates or bicarbonates) neutralize acids and prevent drastic drops in pH. If the alkalinity drops to a critical level, it can cause rapid pH drop and adverse effects for fish and biofilters. For good biofiltration, it is recommended that the water pH not exceed 7.0.

The range is between 100 and 180 ppm, focusing on the levels of carbonate ions and bicarbonate ions. Maintaining a balanced biofilter can be more challenging if species tolerate lower pH or lower alkalinity (discus).

Several management options can stop the drop in pH and alkalinity and any potential increase in ammonia or nitrite.

Routine (once per week to once per month depending on stocking density) measurements of pH and alkalinity and other parameters previously mentioned. Partial water changes on a routine basis (amount depends upon drops in alkalinity / pH over time) as long as the water source has an adequate amount of bicarbonate/carbonate (100 mg/L or more); and ss needed, add sodium bicarbonate (baking soda) buffer.

Hardness, salt, organics, and conductivity are essential parameters that should be monitored. If the system is not subject to routine water changes but is “topped off,” these parameters can increase over time. These parameters could reach unsuitable levels for maintaining or reproducing certain fish species in such a setting.

The water source may contain heavy metals such as lead, zinc, copper, and zinc. You should consult an Aquaculture specialist to determine if they are present. Also, the system should be regularly inspected for any changes. The method may also contain heavy metals such as zinc or copper, which is undesirable. As the pH gets more acidic, they may leach into the water. For the best construction materials, consult an Aquaculture specialist.

Beneficial Bacteria are the Key to Healthy Koi

You should know that you must also take care of beneficial bacteria to keep your Koi healthy. Avoid anaerobic conditions to reduce the possibility of your pond becoming contaminated with unwanted or unhealthy bacteria.

However, there are some drawbacks to the beneficial nitrifying bacteria. These good bacteria can grow slowly, unlike some other bacteria that can multiply by the hour (think of the sand filter). They can be easily affected by low water quality, other than high ammonia levels. Without oxygen, they die within eight hours. Re-colonizing bio-filters with this bacteria can take up to several months.

The pH range required by them is between 7.5 to 8.6.

Like most living organisms, their growth rate is affected by temperature. Chemicals added to a Koi Pond are likely to have adverse effects. You can expect predictable results from antibiotics!

A common mistake is to think that dirty filters are necessary to promote the growth of bacteria. Although bacteria can thrive in unclean environments, harmful bacteria grow. The fast-growing heterotrophic bacteria can compete with slower-growing Nitrification bacteria for oxygen.

Naturally, nitrification bacteria feed off dissolved wastes. Visible wastes are not good food for nitrifying bacteria. Dirty filters can lead to disaster as heterotrophic bacteria living in them can quickly produce byproducts from the decay of organic material. This can cause toxicity or create a hostile microenvironment that hinders nitrification.

Filters filled with sludge and dirt are not recommended for Koi ponds. It is terrible if it smells. There are no unpleasant odors in a Koi pond. Your nose should be a warning sign of trouble.

This means that filters must be cleaned regularly. If they become clogged up with solid gunge, this is likely true. Filters do need to be cleaned. This is a very unpleasant aspect of the hobby and a significant maintenance task for the Koi keeper.

Cleaning the filter system can destroy some or all of the beneficial bacteria colonization. This depends on which stage of the filter system has become dirty. The biofilter stage should never be cloudy.

Maintenance can reduce filter efficiency and cause colonies to re-establish. This can lead to an increase in ammonia levels in the Koi Pond. While reducing the amount of food is an easy way to reduce the impact of filter cleaning, it is not always in the best interest of large-sized Koi to eat. It may take several weeks for the bacterial colonies to recover fully. A pond that has a poor filter system is at risk of disaster.

Trouble can develop over many years. The filtration system’s load increases exponentially as the number of Koi grows, and the size of the koi pond remains the same. Because it is eight times heavier than a 30cm Koi, a 60cm Koi puts more strain on the filter system.


Nitrates are often overlooked. After the nitrification process has been completed by our friendly but temperamental bacteria, there is no ammonia or nitrites left and instead a bunch of nitrates. Although nitrates are generally harmless, new research suggests that they may be linked to fish diseases.

Nitrates are typically used as food by plants. High levels of nitrates can cause a pond with excessive algae growth.

It is best to encourage good algae growth. It provides a place for the Koi to explore, removes some nitrates from the pond, and helps to maintain the water quality. A problem with too much algae is the blanket weed, which can quickly make maintenance difficult and rob the Koi keeper of much enjoyment.

Bacteria can also break down nitrates into nitrogen gas. This is not an easy task. This is known as the denitrification process. This process occurs under anaerobic conditions. I have stressed that we do not want this in our koi ponds or filter systems.

The first step is to reverse the damage done by the Nitrobacter and convert nitrate back to nitrite. The second step is converting the nitrite into nitrate, nitrous oxide, and nitrogen gas.

The problem with nitrates within koi ponds is that creating a large enough denitrifying filter is not practical to do the same job as in aquariums. Also, you need to have a steady source of organic carbon. This would allow the filter to retain some solid sludge. It cannot be easy to control.

The best way to deal with nitrate buildup in a pond?

Water changes and the growth of beneficial algae or Kaldnes biomedia. Popular uses a plant filter, a natural method of eliminating nitrates from a pond by using nitrate-friendly pond plants.

Vegetable filters should be used with care. Remember that koi will eat almost anything and any plant. (to a koi, every plant is a delicious treat!) They will love you for it. You want your plant to tolerate as little soil as possible. This will prevent soil from getting into your pond, which can cause unnecessary strain on your mechanical filter. Anaerobic volumes are also significant. This is because dirt and plants can become too dense. You don’t want the soil to become the breeding ground for parasites.

Active Bed Bio Media



This media is called “Active” because it moves in an agitated condition (using air bubbles for the agitation), and “Bed” refers to the thousands to thousands of tiny plastic tubes that float. “Bio Media” is because it’s designed to grow biofilm – the active location and location of beneficial bacteria that we want to cultivate in our filter system.


The oxygen saturation conditions are maintained for the bio media and thus the nitrification processes. This allows the nitrogen cycle to be completed (i.e., The biofilter is fully used, so there are no dead spots and no areas considered anaerobic.

Active bed bio media has a slight buoyant quality. It can be injected into the chamber housing to mix the media vigorously and turbulently in a chaotic process called moving beds.

This moving bed combines efficient bio-media with water, oxygen, nutrients (ammonia from the Koi), and beneficial bacteria in an ongoing process.

The water saturation in a filter means that the return water to the pond is still saturated with dissolved oxygen. This does not put any strain on the dissolved oxygen levels.

Active Bed bio-media chambers are up to 1000% more effective at removing dissolved substances than static media. Considered one of the main koi pond supplies required on every koi pond.

Because of their incredible performance, the footprints of active bed chambers and vessels are tiny.

Koi benefit from the speed of waste elimination because ammonia concentrations can be reduced much faster than any other biofilter of comparable size.

This bio-media is self-cleaning due to its chaotic movement. Dirt particles and other solid materials are knocked off.

Because the media is self-cleaning, very little maintenance must be done. This has little to no effect on bacteria colonies. Even in the worst-case scenario (total disaster), half of the media can be washed, and the other half can be washed a few weeks later. This results in better physical performance over many years with associated benefits for the Koi.

Continuous rubbing the Active Bed bio-media against one another also remove dead and dying bacteria, encouraging the growth and development of young, hungry bacteria.

The bacteria colony can live an average life span of maturing and growing biofilm inside the tube of bio media.

You can upgrade the biofilters by simply adding more bio media. 

Each 50l of active bed bio media can process 250g of koi food per day.

Air Pumps

Pond air pumps inject oxygen into the water column- and should be seriously considered for every koi pond.

Air-lift-style pumps are also becoming popular due to their low cost, higher oxygen levels, and energy efficiency.


Koi Fish For Sale

Don’t worry; there is no need to fly to Japan to find quality koi fish for sale.  You can easily buy koi online and have them shipped via next-day air.  Many sellers offer guarantees to make sure your koi is healthy and high-quality. With eBay auctions, you can score some excellent deals on all kinds of koi fish for sale. Click on the image to view the auctions to view koi fish price ranges.

koi fish for sale


Koi Fish Breeding Information

A separate pond is required for breeding koi fish.

This can either be done naturally or artificially through hormone injections. Natural breeding will occur in springtime, and the fish will reach sexual maturity at around 2 to 5 years of age.

A breeding pond should have 2-3 males per female. The best spawners are larger, more mature females. It is easier to identify females because the abdomen of mature females is plump. Males are more streamlined and torpedo-shaped. The male pushes the female to spawn by pushing its head and fins against her. Although koi prefer to spawn at dawn, they can also spawn during the day.

Keep your breeding pond at 64-72 degrees F to encourage natural breeding conditions.

The fish should be fed high-protein food, including commercial and natural foods, at least three times daily.

Females will use the shallow-water pond plants to lay eggs. Once they have been applied, the male will fertilize them. This external fertilization is familiar with many species of fish.

Frequently Asked Questions About Koi

Why do Koi have barbels?

These taste-bud-covered organs are used to find food in murky waters. Koi and other carp have four barbels. Two on each side (termed “maxillary barbells”). Although the top two are shorter than the bottom two, they serve the same purpose: taste and not ingest debris. View more information about koi barbels.

When is it okay to start feeding koi after winter?

Generally, you are going to be monitoring the water temperature and adjusting to that.  Read more about when to start feeding koi in the spring.