Going
for growth
This article gives advice on stocking levels and
feeding. There are more koi foods on the market at the current day than ever
before and finding the right food can be very difficult.
The topic of stocking
levels is also hugely controversial as most people tend to have a different
idea as to how many koi they should actually have in their pond. I have been
growing koi on a big scale for five years and have finally been able to begin
to piece together a growing program anybody can follow.
Stocking
levels
There is so much advice available on this topic it can
tend to be very confusing, normally it can be very technical or unrealistic,
for example, in order to get good growth rates you need to keep five koi in
4000 gallons. The majority of koi keepers don’t want to keep this few koi in
their pond as it will look empty, so I have been able to find a balance that
allows very good year-on-year growth rates and doesn’t make the pond appear
empty.
One of my koi houses contains eight ponds that hold
4000 gallons which are set-up exactly the same. When I stock a pond for growing
I always aim to keep the same size of koi together but this isn’t always
possible in a hobbyist’s pond. I only over tend to grow tosai (one-year-old
koi) and nissai (two-year-old koi) and from doing this I have devised a points
system (fig 1) that can act as a guide for anybody stocking a mixed pond or a
professional growing pond.
The points systems will help you when stocking the
pond with tosai, nissai or small sansei (three-year-old koi). If you use this
system in a hobbyist pond I would add 15cm on to the length of the koi before
calculating how many points it will take up. This will allow for the koi
growing in the future and it is most likely that the koi will grow more than
15cm but by making this initial allowance it should set a stocking level that
will more than compensate for this in the future. If you want to maintain
smaller koi in the pond simply work out the points according to the current
size of the koi when placed into the pond. I haven’t included koi over 55cm on the
points scale because when dealing with growing larger nishikigoi there are more
factors to take into consideration and I only over give advice of
professionally growing larger koi case by case.
Figure 1: stocking
rate points
Calculate the amount of points for your pond / 100 gallons =
1 point
Koi size class Amount of points
0 to 18cm 1.5
points
18cm to 30cm 2.5
points
31-40cm 3.5
points
41-55cm 5
points
Is it OK to mix
smaller koi with larger ones?
This is one subject that has always stayed prominent with me
from my time spent in Japan during the selection process where big koi would
always be removed from the fry ponds and transferred into another pond with koi
of the same size. The answer to the question is a mixed one. The teaching I
received in japan was that small koi should never be grown with bigger ones for
example: a yearling around 20-25cm should not be grown with a two-year-old koi
of 35-40cm. The main reason being that the larger koi will always manage to get
a larger share of the food and in the mud ponds will eat more of the natural
food.
However, there are some instances when it is OK to grow mixed size koi
and when all of the koi are 55cm+ as at this size all of the koi will feed
equally as well so there shouldn’t be any serious competition for food. Tosai
growing-on ponds are becoming more popular in the UK – hobbyists are able to
raise a batch of similar-sized tosai up to 35-40cm before placing them in the
pond. This allows them to get better initial growth and be able to compete
better in a normal pond environment.
As a standard rule I would always advise
trying to grow similar-sized koi together to get better results.
Type of food
What food is actually good for your koi?
Everybody has their own reasons for choosing a particular
brand and other reasons for not liking another type of food. I tend to hear a
lot of people saying: “I’ve tried this food for a couple of weeks and it
created a lot more waste and bad water and the fish didn’t seem to like it as
much as the other food.” This is where a lot of the negative criticisms of food
come from.
The initial problem to begin with when trying a new food is that
people will just instantly change the koi from one diet to another and this can
cause large amounts of excessive waste and poor water quality for weeks
especially if the koi had been on their previous diet for some time. It is this
that can also cause the koi to dislike their new food and not eat as well as
previously.
My recommendations when trying new koi foods is to pre-mix
it with the existing diet 50% new food 50% old food for two weeks. After this
period begin to feed your new food only and this should prevent any digestive
problem and help to maintain the water quality. Comparing one food against
another is a difficult thing to do as in
order to make a fair comparison different foods should be tested in ponds that
run exactly the same, with koi from the same batch – koi from the same oyagoi
(parent koi) – and the water temperature and stocking levels also needs to be
the same. I have done this over the years with many different foods and after
testing most of the leading brands on the market today I have always had the
best results with Saki Hikari and Tetra Koi Excellence. I rate the Saki Hikari
as the number one of the market today and most effective in terms of the growth
rates it can achieve but also the development of the koi, general health and
water quality and clarity. The growth diet in particular is superb with a
conversion ratio of 100% so for every kilo fed the total weight of the koi
within the pond will increase by one kilo. The colour diet is also exceptional,
for years I tried to find a colour food that would aid the development of the
koi instead of making them look false or causing it to deteriorate by turning
the white ground yellowish and finishing beni pigment to early.
Saki Hikari colour diet used in moderate levels does
everything I expect of a colour food and I have even raised Shiro Utsuri on this
food without discolouring the white ground. The end results were excellent with
the white ground actually becoming much thicker and the general skin lustre
including the sumi quality was excellent with skin taking on a glossy texture.
The mix I like to use consists of 75% growth diet and 25% colour diet before
moving solely onto Multi-season in the winter. Another added benefit with Saki
is the added pre-biotic the ‘Hikari germ’ – I found that certain fish that
picked up very small surface abrasions would heal without any topical treatment
or antibiotic injection being given. Koi that were fed on this food for a full
season also went through winter much better with no illness and all the fish
tended to be much more active showing the sort of behaviour you get when the
water is 20⁰C but in actual fact the water was only 8⁰C. in my opinion the Saki
Hikari diet is the best and will be my choice until something comes along that
can better it.
Amount
of food and water temperature
Lack of food in relation to water temperature is
possibly the largest cause for koi not gaining the amount of growth they could
during each season. How many koi keepers actually know how much food they are
putting into their pond each day? The answer is simple: not many. Certain levels
of feeding can be given and these levels are calculate from different amounts
of body mass percentages.
The main three are 1%, 2% & 3% and what level to
feed depends heavily on the water temperature. It is important to note that
feeding 1% of the body mass during the summer season is only the maintenance
level – it’s enough food to keep the koi ticking over and healthy. In japan
most koi breeders will maintain the concrete ponds where they grow tosai at 25⁰C,
which is the optimum growing temperature and this is when 3% of the body mass
should be fed. However, when the temperature is below 20⁰C
2% of the body mass is more suitable – anything above this may cause the fish
to become fatty and out of proportion. This could permanently change the body
shape and structure of the koi. Once a feeding amount has been calculated it’s
a good idea to make a food measure with amount of food marked on it so that the
correct amount can be given easily everyday without having to weigh it.
Where a heater is installed, it is beneficial (in my
experience) to heat the pond during summer so water can be held t 24-25⁰C
from may through until October. When this temperature is maintained and the
correct feeding level applied the growth rates will be excellent regardless of
the age of koi, but of course, the water quality must be maintained a mentioned
in part 1 of the series.
Turbo
growth treat
Many different turbo growth treats or
supplements are available today, some of which I think are unnecessary and can
fowl up the system or cause the koi to become fatty. There is one however,
which is heavily used by koi breeders in the mud ponds: silkworm pupae, which
is around 55% in protein. Silkworm can fowl up the system if overfed and I
always advise sieving it to get rid of the dust. The best way to feed silkworm
is two to three times per week as a treat, but it could be fed daily for those
who wish to get the most from their koi. Silkworm is said to make the whole
structure of the koi much larger and a lot of volume can be gained due to it
being a easily digestible, natural source of protein. If you wish to
incorporate silkworm into the daily diet the water temperature must be 24⁰C
or above and in cases where I have done this I made a mix of 50% Saki Growth
25% Saki Colour and 25% silkworm. This in my opinion is the most ultimate
growth mix for nishikigoi but when feeding this sure to monitor the water
quality very closely and good mechanical filtration as mentioned in part 1 is
paramount.
Automatic
feeders
Feeders are very useful piece of
equipment and becoming cheaper. The benefits to be gained from having an auto
feeder are that the feed can split up throughout the day. Fujio Oomo once told
me that I should always use auto feeders because the koi will grow bigger. It
is beneficial having smaller feeds going in throughout the day because the koi
will be exercising on the surface looking for food rather than just giving the
pond one big feed in the morning and another in the evening. The filtration
system can also benefit from smaller feeds because the amount of waste after
each feed will be much smaller so the system will be able to recuperate much
quicker.
Getting
feeding levels right
There may come a time throughout the
growing season when the size of the koi has increased to such an extent that
the feeding level will have to be raised so that the growth level can be
maintained. Should you have to raise your feeding level just try to estimate
the rough growth of each koi and recalculate it accordingly. As well as looking
at increasing the food, take care not to overfeed – some typical signs to look
out for are nitrite or ammonia spikes, especially if the system is well
matured, but also study how long it takes for the koi to eat their food.
Monitoring the time it takes to eat one feed will give you an indication
whether they are being overfed. If the feeding time increases the lower the
feed slightly until the normal feeding time is resumed. Likewise, you can also
use this to judge if more food is required as the koi will eat their feed more
quickly because they have grown and require more food.
Conclusion
Feeding and stocking levels are very
important when growing koi. Getting it right can take a lot of commitment and
observation to ensure you’re maintaining the right amount of food or not
overdoing it. Finding the food that’s right for you can also be difficult,
that’s why it is best to see some results from people (and their koi!) who have
used the food before making a decision.
Notes
Out
with the old
Something i always see as important is the removal of koi that
do not fulfil their potential. I know to a lot of people koi become their pets
so this would be unthinkable but to anybody wishing to get the very best
results, koi that loose their colour or don’t develop to the level of quality
you expect should be moved on to another koi keeper who wouldn’t be quite so
bothered as to what koi they have in their pond. Removing these fish makes way
for something new that holds more potential than the previous koi.
Pellet size matters
To
get maximum digestion from koi food the pellet size is crucial. Most koi food
will state what size of koi the pellet is most suitable for but as a rule I
like to feed a small pellet to any koi of 40cm or under. Small pellets are much
easier to digest due to having a larger surface area. The maximum pellet size I
would ever feed to koi over 80cm would me a large medium pellet so for koi over
40cm a medium pellet is the maximum. Improved digestion will certainly provide
better growth but also better value for money from the food you are buying
because the koi are getting more of the goodness.
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