N03 and Water Changes
Nitrates (N03 ) are best kept under 50 ppm with monthly water changes (less than 20 ppm would be
better). I think the importance of a low nitrate is underestimated. After all, in nature nitrates rarely
exceed 1 ppm. Nitrate levels are a good indicator of other dissolved waste product accumulations and
is a good guide for managing overall water quality. Remember, a high waste content also means a
high bacterial population, good and bad. The numbers of koi most people keep are totally beyond
anything nature ever intended. Large water changes are really the only way to offset this imbalance.
Water changes dilute the pathogens and the organic soup they thrive in. Professional fish breeders
around the world realize this and utilize a constant inflow of new water and an overflow of old water by
as much as 5% to 10% of the pond volume daily. This amounts to over 150% a month. Use caution
with this technique if you are using city tap water with chlorine or chloramines as these will have to be
neutralized. I recommend daily input of 2% daily for city water folk, This is 60% monthly. Chloramines
are less of a problem because of the large dilution factor. On a more practical level make routine
partial water changes and use your nitrate test kit to maintain levels below 50 ppm; under 20 ppm is
best. Many Japanese dealers report levels near 3 and 4 ppm. You may have to increase the quantity
or the frequency of the water changed compared to your current regimen. As far as the koi are
concerned, small frequent water changes are a lot more stable than infrequent large ones. Your koi's
health and color and the pond's appearance will be your reward.
02
Provide and test for high oxygen, at least 7 to 8 ppm. When koi are new or adapting to some stressor,
they will need maximum aeration and it is just best to provide this continuously.
pH
Koi do best at a pH between 6.8 and 7.8. Buffering compounds and water changes will help stabilize
pH near 7.4 to 7.8. 1 have seen apparently healthy koi in pH as high as 8.5; however their colors are
poor. A pH over 8.5 is too high. A pH below 6.5 is too low for the nitrifying bacteria in the filter; not to
mention the koi. Controlling algae growth in the pond also helps stabilize the pH. Excess algae can raise pH over 8.5. Liner ponds tend to drop in pH quickly with insufficient water changes. Liner ponds require frequent pH
tests and would do well with routine additions of a buffer compound. Cement ponds tend to be high in
alkalinity and usually maintain a high pH around 7.5 to 8.5 As cement ponds age the pH will become
less alkaline.
Temperature
Koi prefer a temperature around 74 to 76 degrees F. They are strong and comfortable at this
temperature. A decent and stable temperature is extremely important in maintaining healthy koi.
Temperature stability is maintained in larger deeper ponds with some shade. Koi are very sensitive to
a drop in temperature more than 5 degrees F. Koi lose immunity and vigor when temperatures are
below 60 degrees F. Pathogens are slow to grow in cold water. When the water warms up in spring to
between 60 and 72 degrees the pathogens start growing quickly but the koi is still weak. Maintain
excellent water quality at this time of year and really be careful with quantity and quality of food given.
Koi cannot grow new skin tissue when the water is below 65 degrees. The fish is swimming around
with an open wound, however slight, which will become infected if the water or filter conditions are
dirty. I have seen koi with skin abrasions show no signs of infection until the water actually warmed up
over 60 degrees. These infected and weak koi can carry the infection with them even when the water
warms up into the high 70's. The goal is to catch even slight skin abrasions early; clean the wound;
eliminate parasites; put the koi into warm clean water (76-80 degrees) at 0.5% salt so the skin can
grow back before infection starts. This is especially important for new koi purchased in the winter and
spring, since new koi are usually physically damaged from shipping and handling. Koi are the most
disease resistant in late summer and early fall since the water has been warm long enough to make
the koi strong.
Objects
Keep sharp objects out of the pond when possible. Your existing pond conditions should have smooth
walls and few if any protrusions into or over the pond
Handling
Do not handle your koi needlessly and never lift them from the water in a net. Use a large clear plastic
bag or a koi tub to move or inspect koi. A clear plastic bag with just enough water in it to hold up to the
light will magnify the koi and reveal any damage without hurting the koi.
Population control
Do not overcrowd or overfeed. Do not add koi to a pond that is already overcrowded or is dirty with
sludge. Your filter system, your maintenance schedule, your water changes, feeding practice, oxygen
levels and emergency power supply all determine number of koi per pond. Less koi is always better
than more koi. Zero koi equals zero problems.
Food
Do not starve your koi and feed them variety with fruits and vegetables. Fresh green vegetables and
citrus fruits should compliment koi pellets regularly. Frequent small feedings of pellets are better than
large single feedings. Color enhancers like spirulina and shrimp should only be fed in the warm
summer months to help reduce digestive problems and skin diseases like Hikkui. Most brands of koi
pellet are good as long as they are fresh and used within 3 months.
Protect the Mucous
Most of the aforementioned factors affect the integrity and quality of the mucous on the koi's skin. The
mucous is the koi's first line of defense against pathogens. Over handling and over medication will
strip the mucous off. The mucous has natural protective secretions and good bacteria which can be
removed easily. I have seen koi which were over medicated that basically ran out of mucous. Their
skin was dry and rough to the touch. Use medications thoughtfully and get the fish back into clean
water conditions.
Source of Koi
Buy koi only from reputable sources. Be sure you know the health history of the koi, such as length of
quarantine or time at facility, what if any medications have been given. Note the condition of all the
other koi in the dealers pond and the apparent condition of the pond water.
Do not be overly anxious to get the newest koi before they have had time to recuperate. This is a good
way to throw your money away. Don't think you are going to be the lucky one.
Quarantine and Preventive Treatment
Set up a quarantine pond large enough to comfortably house your largest koi, say 300 gals. Provide a
permanent biofilter and oxygen source; a heater is also helpful. Separate new koi or old sick ones
away from the main pond. This removes a source of infection (carrier state ) from the main
population. This is the same reason we stay home from work or school when we are sick, so we don't
spread it to everyone else. In the quarantine tank you can monitor them closely and give them the
special attention or medications they need.
Salt, Heat Therapy and Other Medications
Although we try our best to maintain healthy conditions and select healthy koi, somehow some still seem to get sick. Boy, doesn't that just yank your chain? Oh, the trials and tribulations! Maintaining pristine water conditions will lessen the likelihood of certain diseases and support quicker recovery when medications do become necessary. Sometimes we have to help weak koi over the hump with some type of medication. I am not going into the endless list of therapeutics. But I do feel a need to mention a few with regards to our main objective which is: All our actions or medications should be aimed at producing a strong koi.
Salt
Rock salt is well known to be one of the most beneficial stress reducers for koi.
Remember when we discussed how a stressed koi loses some of it's ability to osmoregulate properly
across the gills? Rock salt at 0.3% to 0.6% can prevent the loss of internal body salts during stress.
The koi is closer to what is called an isotonic solution. The koi does not have to expend as much
energy recovering these lost salts on top of his already weakened condition. This helps us achieve our
main objective. Also, for some reason, koi seem to be able to handle cold water better and I always
keep these levels of salt in my ponds during the winter and spring. Furthermore salt at these levels
retards or kills many ectoparasites. There is also reason to believe that these levels of salt help koi overcome bacterial infections. How many of you have gone for a swim in the ocean with cuts on your fingers, and found the cuts to be exceptionally cleaner after the swim? Don't we also gargle with salt water when we have a sore
throat?
Salt is definitely a good thing, however, you need to apply a little knowledge
before using it.
Dosage:
Remove excess algae or aquatic plants before using this dose. Salt will kill these and cause pollution and oxygen depletion. Never use salt during a planktonic algae bloom.
Maintain these levels of salt for the duration of the koi's dis-ease by using a pond salt tester or a digital meter for best results. Regular water changes will gradually reduce salt levels over a month or two. There is no need to maintain these salt levels permanently in my opinion.
Alternatively, if you only have one or two koi Which seem to need treatment you may give them a salt bath in a separate tub with 5 gals of pond water and 1 pound of rock salt. This produces a 2% solution. Bathe the koi for only 5 to 10 minutes. Use a plastic bag to transfer the koi to and from the bath so as not to damage skin and mucous,
Potassium Permanganate
This chemical has been used for decades to help control ectoparasites and pathogenic bacterial
problems. PP is particularly helpful in controlling resistant strains of flukes and trichodina. PP is an
oxidizing agent. This means it basically burns or oxidizes materials that it comes in contact with. PP is
non-selective, it will oxidize waste products, algae and pathogens in the water. It cleans the water and
actually improves water quality. Permanganate can also burn the good bacteria in your filter and the
koi's gills if improperly administered. This is where problems occur with excessive use of PP. Koi cannot live in sterile conditions. The good bacteria on the skin of the koi and the surfaces of the pond actually compete for space with pathogenic types. PP can obliterate your natural environment and the koi's good skin bacteria thus leaving a wide open invitation to very fast growing pathogenic types of bacteria. This is a typical case of chronic over medication leading to worse problems. If you need to use potassium permanganate, use it wisely and
quickly and get out of there. Know your pond volume within 5%-10%. For flukes treat at 2.5 ppm every 2 - 3 days until the color remains purple for 7 hours. This should only require a few treatments if your water is clean. For trichodina infestations treat at 1.5 ppm every 2 - 3 days maintaining a purple color for only 2 hours. By
the way trichodina loves dirty ponds and filters.
Fluke-Tabs
These were developed to control resistant strains of flukes and work quite well if applied twice, with
doses applied a week apart. Again, know your pond volume within 10%. The up side to Fluke-Tabs is
that they do less damage to the environment's good bugs than the potassium permanganate. The
down side is their cost to treat larger ponds. Given the less damaging side effects, I would suggest
that Fluke-Tabs extra cost over PP was money saved.
Formalin / Malachite
This old stand by is still very useful for some microscopic parasites like Ich, costia, chilodinella,
epistylus; and fungus problems and some external bacterial problems like early symptom fin rot. The
formalin part of this mixture can damage the environment if over used. Malachite Green is a known
carcinogen. However, correct dosages will overcome many disease problems and is especially useful for new koi or koi coming home from a show. Know your pond volume and treat at least twice with 3 to 4 days between treatments. The Ich parasite will require up to 4 or 5 treatments to kill the life cycle.
To save the pond environment from overuse, do not use any of these chemicals as a general prophylactic. Rather, always use them discriminately when you purchase new koi or bring koi from a show