If a would-be pond or koi keeper were to flick through the pages of a koi magazine, there may well be the danger of them being put off keeping koi by the apparent number of problems that may present themselves to a hobbyist.
Not only can such problems lead to incurring increased expense, but if a health problem or disease is left untreated, it may also lead to the loss of a koi.
Fortunately, not all problems or issues relating to koi keeping will necessarily threaten the life of a fish. It may in fact lead to intrigue by the koi keeper and challenge us to think about how the physiology of a koi works and interacts with its environment. This can be particularly true with the phenomenon of fading colours in koi.
The colours exhibited by koi are seated in the skin which is living, and like other physiological characteristics of koi, is affected by changes to its environment.
There are several causes that can lead to a koi’s colour to fade, some of which we can intervene and respond to but others which are not environmental, but merely a sign of ‘age’.
1. Genetic Factors
The appearance of koi will change with age, be it the appearance of additional patterned areas, or of imperfections such as ‘shimis’, (tiny black spots). These are controlled by genetic factors, within the koi and cannot be manipulated by external intervention by the hobbyist. The same is true of koi with colours that fade, where due to old age, as many different types of cells and tissues become ‘tired’, pigment cells that contain the colour also begin to underperform, causing reds to fade to orange and blacks to turn to grey. All we can do in such circumstances is provide all they require and allow them to grow old gracefully.
2. Environmental Factors that can cause colour to fade.
a. Irritants (Disease and Poor Water Quality)
A host of bacterial and protozoan (single celled) parasites besides causing koi discomfort can cause colours to appear as though they fade. Koi can respond to disease (and other irritants such as poor water quality) by secreting excessive quantities of protective mucus as a protection mechanism. A very simple, globular protein, mucus can give koi and other pond fish a whitish hue when it lies on top of the skin. If on close inspection, excessive mucus is the apparent cause, then a simple skin scrape or water test should identify the likely cause of irritation, enabling remedial action to be taken.
b. Water Chemistry
Besides being an irritant, the chemistry of a particular pond water may lead to fading colour through their being a deficiency in specific minerals.
Pond water that is ‘tired’, and has not been changed for some time, can have a tendency to become acidic through the interactions of the biofilter. Specific minerals can also become depleted as they are taken up and utilised by fish and other organisms and not being replenished. Studies and experience has shown that colouration in pond fish is enhanced when koi are kept in hard, alkaline water with a comprehensive breadth of minerals. Colours can be enhanced by the addition of montmorillonite clays that release a complement of minerals into a deficient water, leading to an improvement in colour.
Koi and other pondfish are only able to exhibit pigments if they receive them (or their pre-cursors) from their diet. Pigment cells in the skin store carotenoids (a group of natural pigments) relative to the type of pigment cell. For example, a black pigment cell will store black pigment, red cells – red pigments and so on.
Carotenoids are provided in the diet, and koi can manipulate and change a number of pigments in the diet to those expressed in their skin. In the wild, fish obtain carotenoids from animal and vegetable matter that they consume when browsing on natural flora and fauna. As this is not possible in the typical koi pond, carotenoids must be provided in the diet we offer. Ensure that the food your koi are fed has a good balance of natural and artificial colour enhancers that can provide your koi with sufficient quality and quantity of colour enhancers.
Learn from the professionals.
It is very rare for the colours of koi that are farmed in natural mud ponds to fade. In fact, such conditions are recognised as bringing out the best in koi health and colour and it is once they are removed to clearer water that their colours tend to deteriorate. What is the reason for the success enjoyed by the professionals? -Ponds with a clay-rich substrate and a high and complete mineral content and copious amounts of natural livefood. Excellent for health, growth and colour, but not for viewing!