Koi in Ponds: Skin, Scale Beauty & Care of Koi

Page Summary: It might be the lustre, the bright red, the metallic sheen that attracts you to a koi. When all is said and done it is the outward appearance of the koi in a fishpond that attracts us and persuades us to also take out the wallet and buy that beautifully coloured koi. Most people buy koi when they are small and showing beautiful markings, sheen, lustre and colour variations. What most people dont know is that it is highly unlikely that those beautiful colour variations and patterns to be seen in your small koi will carry through into adult life. But that shouldnt detract any pond keeper from selecting and buying young koi based upon their colour and variations in pattern. Just bear in mind that there will be no recourse when that magnificently coloured young koi becomes a fairly drab poorly marked adult koi.


Koi Skin and Scale Care

Since koi are kept first and foremost for their ornamental beauty, proper skincare is a pertinent subject for any serious koi keeper. Although it may seem like koi scales are responsible for the vivid colours and attractive markings that we admire on our koi, the reality is that this fish’s beauty is really only skin deep. Contrary to how it may appear, a koi’s scales are actually positioned below its skin, which indicates just how thin and sensitive the skin is. It’s a common misconception that koi scales form a protective covering over the skin when, in fact, the opposite is true. So, what should you be doing to ensure that your kois’ most precious asset is protected and cared for? It helps to know what constitutes healthy koi skin and scales, as well as what the warning signs of disease and injury are.

Healthy Koi Skin

Koi skin fulfils a vital protective role by secreting mucus that wards off harmful bacteria.

The mucus acts as a shield, which is why koi secrete extra mucus when they are stressed or have to fight off the negative side-effects of poor water quality.

The way to tell whether koi are secreting surplus mucus is to examine their colouring. Do their red and black markings appear more orange and grey?

This is most likely a sign that your koi have secreted more mucus than usual, as the thick mucus layer will cause their vivid markings to look noticeably paler.

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Colour-determining cells called chromatophores are located in the deeper dermis of a koi’s skin. Depending on the genes that koi have inherited, their colouring and markings will change and develop over time. A variety of colours are developed from corresponding chromatophores, while black markings are produced by melanophore which is found near the epidermis. In order to protect these intricately coloured creatures, you need to handle them with care. As koi skin is so fragile, it’s best to avoid handling your fish unless it is entirely necessary – and even when it is necessary, koi should be caught with very soft hand nets and should be held with wet hands.

If you suspect that your koi may be suffering from an outbreak or increase in pathogenic organisms, a mucus biopsy can be carried out to determine the cause. This too should only be done if it is entirely necessary, as there are additional risks involved with removing some of the protective mucus. A glass slide should be drawn over each dorsal flank in order to get a sample which can then be examined under a microscope.

Removing Loose Scales

In the same way that the age of a tree can be determined by counting the bands on its trunk, a koi’s age can be worked out by counting the bands on its scales. Each fish scale will have evidence of the seasonal periods of growth that your koi have undergone. If you ever have a chance to examine a fish scale on its own, you will see that it has no colour. The function of koi scales is to serve as another barrier of protection, overlapping each other to allow for flexibility.

Koi are not able to regenerate lost scales. They have a set number that develop in size along with their own growth patterns. However, if any scales come loose or are damaged through an unfortunate chain of events, you will have to remove them. The best method of removal is to use a sterilised pair of tweezers to extract the damaged koi scale in one quick motion. Afterwards, you should treat the extraction site with anti-bacterial ointment to prevent any infection.

Top Tips to Enhance Koi Skin

If you want to enhance the colouration and overall health of your kois’ skin and scales, it all comes down to diet and minerals. Koi are able to take in minerals through their diet and via the pond water. To ensure that they are getting sufficient minerals, you should increase the calcium and magnesium levels in your pond water.

Another excellent source of minerals is clay. Regular addition of clay will replenish the mineral content of your pond water, improving its clarity while also providing for the mineral requirements of your koi. Koi colouration can also be enhanced by making certain that there is enough carotenoid in their diet. A koi’s colours will become noticeably more faded if they are given a diet that is deficient in carotenoid.


Dont stress over pond pH and Testing Koi Pond pH

Interpet Koi Pond Test Kit

I will make a few very important points here which should be taken very seriously by anyone contemplating measuring pH in a koi pond and then TAKING ACTION based upon the measured result from testing the koi ponds water. If you test do it reliably... Interpet lead this pond water testing field of the koi keeping hobby

  1. pH of koi pond water will vary depending on time of day measurement is taken and especially if plants are in the pond. This means if you take a pH at 9am it will not be the same as a pH taken at 6pm. This single piece of information therefore must never be the information relied upon to make fundamental decisions
  2. pH is notoriously difficult to measure even in a laboratory with sophisticated instruments let alone in a koipond or fish pond using a piece of litmus type paper or a vial with coloured scales on it.
  3. If you must measure pond pH and this is a great part of the hobby then take the pond pH at the same time every day and plot the result on a graph. So now what youre looking for is not a single pondwater result but rather a pH trend in the pond water that you can use to sensibly consider a pH strategy.
  4. Very high pH in a koi pond is a serious threat to the well being of koi when levels reach about 9.5 because at this pH level ammonia which is a natural metabolic product of the koi and its existence becomes extremely poisonous
  5. It would be extremely rare for a koi pond to reach dangerous pH levels but could well occur in koi ponds with serious algae problems

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