| Ornamental Koi are mostly bred in Japan and | | | | Pond Depth |
| shipped to rest of the world. Many years of | | | | Pond depth should ideally be at least 1.2 meter or |
| selective breeding had led to development of | | | | about 4 feet. Pond surface area is usually limited |
| various colorful varieties of Koi but all will need the | | | | by the space available in our home or garden. A |
| same water requirements. They are relatively | | | | deeper pond would allow for greater pond volume |
| hardy fish and can tolerate poor water conditions | | | | per unit pond surface area. A deeper pond would |
| but not for prolonged periods. If you are serious | | | | also help keeps the water cooler in hot, sunny |
| about Koi keeping, then continual good water | | | | weather. Hence, a deeper pond is good for the |
| quality is must to maintain your Koi at their peak | | | | Koi growth but one has to be mindful of the |
| condition. A pond for keeping Koi has more | | | | proportion of the depth versus size of the |
| stringent requirements compared to a normal | | | | pond.pH levelpH is a measure of the acidic or basic |
| garden pond. | | | | (alkaline) nature of a solution. Normal tap water or |
| Pond Size | | | | fresh water should have pH level of 7. Water with |
| Although most Koi sold are young Koi and | | | | a lower pH level is deemed acidic while alkaline |
| averages from 20 cm (yearlings) to about 50 cm, | | | | water would have higher pH. Chalk, limestone, |
| Koi can grow to as large as 1 meter in length. | | | | coral or seashells dissolved in water will produce |
| Size and bulk is one criterion when Koi are judged | | | | higher pH. It is important to maintain the right pH |
| at Koi shows. Koi need space to thrive and some | | | | level for the right type of fish. For example, |
| Koi experts have claimed that growth rate is | | | | African cichlids which originate from Lake Malawi |
| proportional to pond size and volume of water | | | | requires high pH and a rocky environment, while |
| per Koi. | | | | South American tetras and cichlids which originate |
| Just like in aquarium fish keeping, a larger volume | | | | from the rivers of Amazon require low pH. Low |
| of water or pond would also provides more | | | | pH or sudden drop in pH level kills Koi and many |
| stability in the water condition. Often, this is limited | | | | other fishes. It is generally better to have pond |
| by available space for your pond and usually not | | | | water for Koi at with slightly higher pH (7.4 is ideal. |
| by cost. I am not sure about other countries, but | | | | Not more than 8.0). Water test kit can be used |
| in Singapore, my pond builder has told me that I | | | | to measure pH. Many Koi keepers, myself |
| can have a slightly larger (or smaller) pond for the | | | | included, placed coral and seashells in their filtration |
| same price (like buying a shirt!). If you are planning | | | | system to maintain or buffer the water from |
| to keep 9 Koi (each about 70 cm long), the pond | | | | sudden pH level changes in their Koi ponds. |
| dimensions should be at least that of a king-size | | | | Ammonia, Nitrite and Nitrate |
| bed. Believe me, once you are bitten by the | | | | Fish produces ammonia as a waste product and a |
| Koi-keeping bug, you would not want to stop at 9! | | | | good filter system must be provided to remove |
| Hence, you should go for the largest pond that | | | | this ammonia from the water. If a biological filter |
| you can fit into the available space in your garden | | | | is used, the bacteria in the filter will convert the |
| or house. | | | | ammonia to nitrite and then from nitrite to nitrate. |
| Oxygen level | | | | Nitrate is relatively less harmful to fish and Koi |
| Koi needs oxygen and so does the bacteria in the | | | | than ammonia or nitrite. Ideal levels of ammonia |
| biological filter. Dissolved oxygen level of 8 mg | | | | and nitrite should be zero or near zero and this |
| liter in water temperature of about 25 deg C is | | | | can be achieved using a good biological filter |
| almost ideal since it is almost at saturation point. I | | | | system. Nitrate level should be less than 25 mg |
| used a water test kit to measure this. Note that | | | | liter. I used a water test kit to measure nitrate |
| plants (including algae) in the water also use | | | | and nitrite levels. The only way to reduce nitrate |
| oxygen at night. Plants take in carbon dioxide and | | | | is through partial water changes. Water plants to |
| produce oxygen only in the day, during | | | | absorb the nitrate but may not completely |
| photosynthesis. Some form of aeration in your | | | | remove all nitrates from your pond. Excessive |
| pond design is a must. Oxygen is absorbed by the | | | | nitrates may lead to algae bloom and turn your |
| water when it comes in contact with air. Any way | | | | water green. Koi needs to eat regularly and eats |
| to increase the interface area between the pond | | | | a lot to maintain their bulk and grow to their |
| water and air would be good. This can be | | | | fullest potential. This means a lot of waste matter |
| achieved through use of a waterfall, fountain, | | | | is produced and have to be processed by the |
| venturi pipe water return system or air pumps | | | | filtration system. A rule of thumb is that the size |
| that create streams of bubbles in your ponds. | | | | of the filter system should be one-third of your |
| Temperature | | | | pond size. Specially designed, all-in-one filter |
| There is a need to keep the water cool, especially | | | | system available commercially may be able to |
| during summer or if you live in hot, sunny country | | | | achieve the same effect with a reduced size. |
| like Singapore where the daily temperature ranges | | | | Learn how to keep water, then the Koi will keep |
| from 25 deg C at night to 34 deg C in the day. | | | | themselves. Hence, building an adequately sized |
| Warm water does not carry oxygen as well as | | | | pond with a good filtration system is the first |
| cool water. In any case, some shade would be | | | | step towards having good water quality and |
| good for the Koi. I have read about Koi getting | | | | healthy Koi. Regular water testing and partial |
| sun-burnt from prolong exposure to direct sunlight. | | | | water changes are essential too. |