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Pigmentation - Making the whites
whiter, and the colours brighter
One of the greatest challenges in keeping koi is
to optimally enhance their unique natural colour patterns
by combining various food or food pigments. Some background
on the origin and correct application of these pigments follows:
Numerous koi breeders and enthusiasts have mastered the art
and science of breeding top quality fish but have often failed
to successfully compete during koi shows due to faded colours.
Besides vitality, body shape, fin shape and size, an important
characteristic affecting show quality of koi is body colour.
In order to successfully compete with other koi, it must be
well pigmented to bring out definite colour patterns. Various
food combinations, some containing commercially available
carotenoid pigments, have successfully been used alleviate
this problem making it no excuse to effectively enhance skin
colour.
Carotenoids are a group of over 600 natural fat-soluble pigments
that are primarily produced within phytoplankton, algae and
plants. These pigments are responsible for the broad variety
of colours in nature; in plants, the carotenoids are found
in green plant matter and as petal and fruit pigments, whereas
in animals, the carotenoids are mainly found in the exoskeleton
of crustaceans (i.e. shrimp and crayfish) and insects, the
flesh and skin of many fish species (i.e. trout and salmon)
and the plumage of a number of birds (i.e. flamingoes). The
reddish pigments (astaxanthin & canthaxanthin) are the
most widely distributed carotenoids in the animal kingdom,
followed by the yellow ones (lutein and zeaxanthin).
Microorganisms, fungi, algae and higher plants are able to
synthesize carotenoids; however higher animals are dependant
on obtaining carotenoids from their natural diet. Practically,
pigmentation can therefore be achieved naturally by raising
koi in a pond containing carotenoid-rich algae. Although this
conventional method of stimulating koi colour is feasible
it is not practical in the “relatively confined”
areas in which koi are kept in garden or koi ponds. Furthermore
algae blooms can be quite detrimental to the koi’s health
due to water quality problems as well as by dramatic oxygen
depletion especially during cloudy days or during nighttime.
Under pond conditions where the natural source of pigments
is not available, comparable colour can therefore “only”
be achieved by the supplying various sources of carotenoids
via supplementation of the koi food with isolated carotenoid
pigments. The most commonly used sources of pigments in commercial
koi foods are the following:
- Natural sources that provide a platform
for the growing interest in developing organic food concepts
based on natural food ingredients.
Spirulina algae, probably the best-known source
of pigments used in commercial koi foods.
Haematococcus pluvialis, a unique strain of micro-algae
and an excellent source of astaxanthin.
Phaffia Rhodozoma, yeast specie producing copious
amounts of astaxanthin
Shrimp offal meal and other animal by-products
not suitable for human consumption.
Other natural sources include raw materials such
as yellow maize, alfalfa, paprika, marigold petals etc.
- Koi food can also be enriched with synthetic,
but still nature identical carotenoids. This means they
have exactly the same chemical structures as the natural
ones and are absorbed and deposited just as effectively
as the natural form thereof. They are however much more
concentrated and more stable, making their inclusion in
commercial koi foods more efficient.
Pigmentation may often be quite unpredictable due to a possibility
of certain unforeseen factors:
- Poor feed itake, often caused by nutritional imbalances
or poor environmental conditions (poor water quality, extreme
temperature, etc.), may influence the rate of deposition
negatively.
- Gonad development during sexual maturity has a negative
influence on colouration due to an increased nutritional
demand.
- Some of these pigments also serve as forerunners for
the production of vitamin A - therefore in times of vitamin
A deficiency in the fish will use the pigment to synthesize
vitamin A instead of colour-deposition. This occurs especially
during conditions of stress, such as transport handling,
extreme temperatures, disease occurrence
Koi with vivid colours adds “atmosphere” to any
garden pond. In order to successfully enhance these colours
a stringent feeding regime should be followed, using appropriate
colour-enhancing koi food form a trusted manufacturer. Although
pigmentation can already be noticed after a one-week use,
it is recommended that a minimum of a 4-week pigmentation
programme should be followed to ensure positive results. This
of course depends on the pigment content of the koi food and
the reliability of the manufacturer. There is an abundance
of colour-promoting koi food on the market, contact the manufacturer
directly and enquire about their specific pigmentation recommendations.
Lourens de Wet
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