Page 73 - Koi Net - On-Line Koi Magazine - Issue 92
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going to thrive along with algae (phytoplankton = perhaps that during the natural grazing behaviour of our
depending on photosynthesis, the sun), which are eaten Koi they also end up in their intestinal tract and offer
by small creatures such as lobster-like (zooplankton). some nutrients. However, this cannot be much. In our
The algae converts the Ammonia and nitrate present to ponds, the Koi depend on the pellets we give them. This
grow and divide into more algae, and this is eaten again also explains the many skinny Koi that I unfortunately
by all kinds of small creatures. If this grows well for a regularly see in ponds of people who give cheap goldfish
while, you’ll also get bigger worms and slugs, like sticks and the like to Koi, or just very little food. The Koi
Macrophytes that live happily at the bottom feeding on do not just gather enough or even almost enough
the bacteria and zooplankton. If carp are added, they’ll nutrients from the wall of the pond. But that’s simply my
eat all the worms first, especially if you add older carp conclusion after my literature research and reasoning
(above 150 grams, i.e. 2 years old or Nisai). The older regarding the Koi ponds and ponds with Koi that I’ve
carp have a distinct preference for the worms. When seen. Aren’t you convinced yet, if you have a beautiful
these are finished they start eating the zooplankton such big pond, well-functioning big pump and a drum filter?
as water fleas and the like. These are smaller and they The sieves on the drums usually have mesh sizes of 70
will use a little more energy compared to the nutrients to or 100µm. The water fleas are bigger, so every time they
be absorbed, but they like them. In ponds where too escaped passed the Koi, they are drawn through the
many carp were put in, more than 200kg per hectare bottom drain to the drum which removes them from your
(100 × 100 metres pond, 1 metre deep mostly) the pond system.
worms were finished in no time. However, when pellets
were added as a food source, the carp first went to eat My conclusion: virtually all Ammonia comes from the
the pellets and up to 1,000kg per hectare could be food in your Koi pond, and also (almost) all the nutrients
kept before the worms were targeted and eaten. An that the Koi uses and converts into Ammonia, come from
average Koi of 5kg is 65cm, so with more than 200 carp the food.
per 10,000m³ or 1 carp per 50m³ there was soon no However, after this already long piece of information I
more worms, despite being fed, in this large green thought I would share with you, I finally came to my main
puddle of water. At more than 1628kg/hectare or 1 carp question. Where does all that nitrogen in our ponds go?
of 65cm per 30m³, this went completely wrong and had What can be thought of, determined and proven?
a major negative impact on water quality and the
ecosystem including natural food sources. How long What we always learn in the Koi hobby is that most of
would the worms survive in a beautifully clear Koi pond the Ammonia is converted by the bacteria into nitrate
with 1 Koi of 65cm per 2m³? And when these are eventually, but then what? We remove a portion through
finished, the Koi are going to look for all zooplankton, coarse filtering and water changes, a part can leave the
like water fleas. How long does the water flea survive in pond with blanket algae and people with plant filters
an average Koi pond? I’m guessing an hour. I had the extract some extra nitrogen from the pond through that
pleasure of a large plant filter in my previous garden and route. But most of the Koi ponds do not have plants or
grew the water fleas in it. Every day I went through that not enough, and older ponds also hardly suffer from
water with a fine net and put some water fleas in my Koi blanket algae. How then? And can we find evidence for
pond. That’s when they all vigorously attacked that denitrification, or gasification to N 2 gas in our ponds?
feast. I had to add some every day because I never The main routes were described in detail by Ebeling in
found 1 water flea back in my Koi pond. The articles on 2006. Ammonia can be used by phototrophs (using solar
mudponds and natural food clearly state that larger Koi energy, Algae), autotrophs (bacteria such as Nitrobacter/
in particular do not use phytoplankton (the bacteria and Nitrosomonas/Nitrospira that extract their energy from
large single cells) as a significant nutritional value. There Ammonia or nitrite) and heterotrophic bacteria (bacteria
are undoubtedly some larger single cells amongst the that use a carbon source for energy such as sugar or
bacteria in the blanket algae on my pond wall, and
sludge components).
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