Living Jewels

Appreciating Koi


Keeping Koi is one of the most fascinating hobbies. Relaxing next to the pond watching the fish swim about lazily is a very pleasant occupation. There is so much to learn and appreciate, that the Koi keeper can spend many hours researching the subject. Large Koi can become extremely tame, and will learn to eat from one’s hand. Often the Koi develop particular personalities and behaviour patterns.

The first Koi

Koi originated in China about 2500 years ago, when the word was first used to describe the fish. There are different versions of the story, one saying that Confucius was given a fish named “Koi”. The other story is that Confucius named his son Li (literally meaning Koi) because he wished his son to be as orderly as the arrangement of scales on the back of the Koi. Koi were also considered to be a symbol of strength.

These early Koi were carp, and bred from the Magoi or black carp line. The first mentions of coloured carp occur in manuscripts from about AD 250 that tell of red, white and blue coloured carp.

The early mutations from the original black fish would have been red or white and cross breeding would have resulted in a Koi much like the Asagi (blue-gray and orange/red) of today, since the Hi (red) appeared on the belly of the fish. Later, a white fish with red on its back was developed which became the modern Kohaku.

In Niigata Prefecture, a beautiful, mountainous region of Japan, Koi were first bred as a food source. The inhabitants were often cut off from the outside world by snow during winter. Today, it is the home of many of the finest breeders of Koi in the world. The secrets of breeding have been passed down from generation to generation.

Modern Koi varieties

Koi breeders in Japan have now developed many different varieties.

The most popular varieties are: Kohaku, Sanke, Showa, Bekko, Utsurimono, Asagi, Shusui, Koromo, Goshiki, Tancho, Kinginrin, Kujaku, Chagoi, Ogon, Ochiba Shigure and Hariwake.

The names of Koi can confuse the novice totally, as within each variety, mutations showing Doitsu ( no scales) Koi with metallic lustre such as the Ogon and Kinginrin ( shiny scales) add to the vast array of wonderful Koi that are available today to the dedicated collector. It is not surprising that a beginner wonders if the names will ever be mastered. However, with the help of a knowledgeable dealer, the mysteries of Koi can easily be grasped.

Find out more about these varieties in this article.



When selecting Koi for your pond, it is important to decide whether you plan to keep Koi purely as a hobby or whether you want to become a collector with only top grade fish. Shiny, brightly coloured Koi, such as the Ogon, Kinginrin, and Doitsu varieties, will often attract the novice.

A balanced collection will have as its basis, a number of Kohaku (red & white) Sanke (red, white with a little black) and Showa (black, red & white). There will also be a selection of other varieties giving colour and balance to the collection.

Rather try to buy the best quality small fish, which has a good future, than numerous cheaper, inferior fish. A fish that is not good as a baby does not have much chance of becoming beautiful in later life. It is however, important to know that in some varieties, small Koi that are good quality, do not necessarily look good until they have matured. These are called “Tategoi” meaning Koi with future potential. Again it is supply Oxygen to your fish and the filter. Your pump must run 24 hours a day.

• Water in a new pond system should be de-chlorinated and the PH stabilised before adding fish. The above is true for any future water changes. Rainwater can also affect the PH. The PH should be between 7 – 8.5.



The Koi keeper will need to test for the following in their Koi Pond in order to establish that the water quality is suitable for their fish.

• AMMONIA – a metabolic waste product excreted through the gills of the fish, and through the decomposition of organic matter. A high concentration of Ammonia will be toxic to fish. If toxic levels are reached, immediate action is needed. Stop feeding, do a water change and check that your filter is working. Remember to de-chlorinate the water when changing water. If the Ammonia levels remain high it may be that your filter needs to be up-graded. Please contact Koi @ Jungle for advice.

• NITRITE – produced by the oxidation of Ammonia by aerobic bacteria (in your filter) or by the reduction of Nitrates by anaerobic conditions (heavy layers of organic matter in the filter or pond)

• NITRATE – not acutely toxic, but detrimental in high concentrations in the long term. Nitrates can be corrected by frequent small water changes and by having a stream with water plants, which utilise the nitrates in the water.

• PH – ideally should be between 7 – 8.5. Koi will suffer if the PH drops below 7. Highly acid pond water will cause loss of appetite, listlessness, or a white film on the scales and in some cases death. A low PH can be corrected using Bicarbonate of Soda or using crushed coral in the filter. A very high PH is not advisable either. In this case, please do not attempt to correct with pool acid, but rather choose a more natural product such as peat moss.

Four easy steps to successful koi keeping.

Koi keeping is a fun and exciting hobby and if you follow the 4 steps below you can have a clean and algae free pond with very low maintanence. Step 1. Large Mechanical filtration system Step 2. Fine Mechanical filtration system Step 3. Biological filtration system Step 4. Ultraviolet light. Over the next two editions of The Fishkeeper I will write on the 4 steps above that can help you with your koi pond.


Step 1 – Large mechanical filtration

Bottom drains collect the dirt and organic matter that then get sucked into the large mechanical filtration system, know as a settlement chamber or dump tank. The settlement chamber consists of an external box that sits at the same level as the pond and traps suspended solids in its filter brushers. The brushers are used to trap or settle down the solids and the box is sloped to one side with a bottom drain for easy flushing and routine maintanence. The settlement chambers job is to trap the large solid particles before they get to the biological filter so that the solids do not block the water flow in the bio filter and shut down the system.

There are different sized settlement chambers available depending on your koi pond size. When you are looking to purchase a settlement chamber make sure you buy the correct size depending on your water volume.

Step 2 – Fine Mechanical filtration

This can be a koi sand filter or a bubble bead filter. If you choose a koi sand filter water from your koi pond will pass into the flter, where it is filtered through sand contained in a pressure cylinder. The sand filter removes fine solid particles from the water and remember only koi sand of around 3-5mm must be used. If swimming pool sand is used it will block up very quickly and clog the system. Koi sand filters are more affordable than bubble bead filters however if you do not want to do to much maintanence then the bubble bead will be your filtration of choice. The bubble bead filter looks very similar to a sand filter with the exception of a Jacuzzi blower attached to it. The internals of the bubble bead work completely opposite to a regular sand filter in that instead of the fingers sitting at the bottom they are on top. This is because the plastic media floats to the top and thus the filter draws clean water through this floating media. There are many benefits to this floating media. Firstly most of your solid waste, which gets trapped in the media, will automatically fall to the bottom of the filter thus reducing clogging. Secondly the plastic media will also give you better polishing of the water than sand with the added benefit of boosting your existing biological filtration. Backwashing and maintaining the bubble bead is where the best benefit comes in as the blower replaces the manual labor.

Angela Beckx