Koi-keeping is a relaxing, stress-relieving hobby. Koi are intelligent and can be taught to eat from your hand. They can also hear well and respond to your voice! Koi appreciate in value as they grow.
The word Koi comes from the Japanese word ‘Nishikigoi’, meaning ‘brocaded carp’. The average lifespan of a Koi is 25 to 30 years. They are social and get along with most freshwater fish. There are more than 80 types, in various patterns and colours.
Tips on starting your own Koi pond:
- Your pond Choose an area in sunlight for your water plants. The bigger the pond the better – this reduces temperature fluctuations. Your pond should be about 1.5m deep in the deep end and about 600cm in the shallow end, providing varying water temperature. Koi experts advise that the pond be built professionally. Once the pond is complete, run the water through the filter/pump for a few days before adding fish. Check that the water circulates properly.
- Water plants These provide shade, oxygen during the day and a hiding place for Koi from birds and other predators. They also help to reduce algae. Keep the salt concentration of the water low. With plants, limit it to 0.1% (1.35kg/1,000L). The ideal concentration for Koi is 0.2% (2.7kg/1,000L). Make sure you don’t introduce any plants which are toxic to Koi.
- Filtration You can use a mechanical sand filter (more expensive, can clog and can develop bad bacteria, but neat, low-maintenance, easy, and filters large areas), or a biofilter (large ones are needed – they create the bacteria needed to break down ammonia. Clean every three months with pond water, to avoid killing good bacteria).
- UV light Unless you will only have a few Koi, a UV light is essential in South African weather conditions. Water from the pump flows over the UV tube into the pond, helping to kill algae.
- Water conditions If your pond’s water conditions are unsuitable, your fish will die. Fish produce toxic ammonia in their waste. Nature’s nitrification cycle solves this problem. Bacteria called Nitrosomonas break ammonia down into Nitrites. Nitrites are also deadly to fish, but Nitrites are broken down by another bacterium called Nitrobacter, into Nitrates which are beneficial to fish and plant life (not exceeding 50ppm). A new pond and biofilter need time to develop these bacteria. Leaves, sludge and debris build-up cause development of bad bacteria. Check the chemical balance (PH and ammonia) once weekly, more regularly in summer, and with changes to the pond. A pond test kit is essential. Weekly water changes are beneficial, with dechlorinated or ground water. Don’t overcrowd the pond with too many fish.
- Choosing Koi Only buy from reputable dealers, breeders and Koi keepers. Koi are valued according to shape, pattern and elegance. Koi should be symmetric in shape and free of deformities. The patterns should have no blemishes; their edges should be sharp. Stains on their fins, head or face make them less valuable. Their colours must be deep and pure. A Koi who swims gracefully has more value.
- Transportation Guide the Koi into a tub. Put one fish in per plastic bag, with enough water to cover the body and fins. Fill a large bag with oxygene, or air from a pump. Add five to ten times the amount of oxygen as water. Leave enough surface area in the bag to allow for gas air exchange. Keep the bagged fish out of direct sunlight and as cool as possible. Never add water to the bag. The PH shoots up and converts ammonium to toxic ammonia. Release the fish as soon as possible unless there is a big difference in water temperature. Do not release the water in the bag into the pond; it might contain parasites and will contain ammonia. Gently place each Koi in the pond/quarantine facility, with your hands or a soft net.
- Quarantine Put new fish and plants in a separate, netted 1,000L pond before integrating them into the main pond, to prevent the spread of diseases. Let them settle in and move them within four weeks if healthy. Make sure this pond has adequate oxygen and circulation. Monitor your fish, don’t over-medicate and don’t feed for a couple of days. Check the filtration, PH and temperature regularly. Add 3kg salt per 1,000L water for fish, and no more than 1% concentration/100g per 100 litres for plants.
- Feeding Koi will live off algae and insects, but you can also feed them. Provide quality food and vitamin supplements, available from good pet stores. Feed them roughly once a day. Only give them as much as they’ll eat in a few minutes – excess food decomposes and affects water quality. Avoid feeding in deepest winter when they hibernate and don’t eat much.
- Diseases Koi are hardy, but do get diseases. Injuries also happen – treat these immediately. Put sick fish in a separate tank and treat them accordingly. Watch out for sunken eyes, gasping, mucus, head-hanging, ulcers, haemorrhaging and gill necrosis (breakdown). Take a scraping from the scales of the sick fish to your nearest specialist vet for testing.
Get to know your local Koi clubs, societies, websites and vets for more information on Koi care; they are happy to help with advice for your fish.