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Myths, Mysteries and Fallacies

Filter bacteria: Fragile things?

The fables handed down through the years about filter bacteria include:

Certain chemicals would devastate the filter and pond of beneficial bacteria.

Washing out filter media with anything but pond water would wash off the beneficial bacteria.

High flow rates through the filter will wash off the beneficial bacteria

Major water changes would eliminate most of the disease pathogens in a pond.

Well it is not true. There are now numerous scientific studies that have proved beyond doubt that the Biofilm formation of bacteria that adheres to a solid surface is virtually indestructible. It is the leading cause of many nosocomial infections in hospitals growing inside of catheters, and implanted devices. This protective environment can exceed the mass of the microbe cell by over 100X, which makes it a very protective environment from the outside world. The industry has found that Biofilms are so resistant to destruction that is some cases water treatment plants have had to sand-blast the microorganisms from surfaces.

The medications that are commonly used in our Koi Ponds to eradicate pathogens will not fully penetrate these Biofilms in the filter systems to kill all of the beneficial or bad bacteria. The free-floating bacteria are killed more easily with chemicals. These chemicals are usually stopped in the beginning when it becomes depleted to inefficient levels when coming into contact with the Biofilm. Although a certain amount of growing Biofilm layers may be penetrated, or sloughed off but the newly exposed layers begin to grow that previously laid dormant due to the starvation from nutrients. The Biofilm now starts to rebuild its lost layers. This means that the most common result is a small Biofilm and large free floating bacteria kill rate.

The microbes in the Biofilm are almost bulletproof in this sphere of slime and can stay active for days and even weeks when fully dried out. Now one can understand why ponds recover so well after chemical treatment, and why diseases are never fully eradicated. It is due to Biofilm existence and its incredible protective properties.

Last Updated on Friday, 08 October 2010 14:16


The word Tategoi is probably the most overused, misused or abused word amongst the Koi fraternity. The fact is that a Tategoi is a koi that has survived the strenuous culling processes of dedicated breeders for one or many seasons purely on the grounds of the perceived potential to improve to become a serious contender at major shows by the breeder. The breeder with the knowledge of a particular bloodline passed down to him through the experience of many generations is actually the only one who can confidently label a specific koi as Tategoi. Still the label comes without guarantees and the risk remains with the purchaser.

Now for dealers that had not even set an eye on the parent stock, let alone the previous progeny, the easiest way to sell a Koi is to label it Tategoi, triple the price on it and leave the hobbyist to it. If the Koi doesn't develop it must have been something the hobbyist did or didn't do! This tactic works at a koi show. Just walk around the koi shows and listen to the sales talk! Whether the same customers will return next time is open for argument.

Even if one dealer is fortunate and rich enough to obtain a real Tategoi from Japan, please consider the following. Mr. Tokutake, certified ZNA Koi Judge, is quoted on www.koi.com:  “Keeping Tategoi is never an easy task. When I purchase 10 of the highest grade Tategoi in the spring, even if one of them turns out the way I had hoped for at the end of the growing season, I consider myself very fortunate”.

Last Updated on Friday, 08 October 2010 13:39


When you get involved with Koi and all the fascinating aspects of the hobby, it is sometimes so overwhelming that it is normal to feel totally inadequate in the presence of more experienced Koi keepers. The fact is that one feels intimidated with the use of Japanese words and just when you think you know some of the words, you realise that your pronunciation of the words is such that you must repeat the word several times before those around you would understand what you are trying to say.

In awe, you listen and absorb the “facts” that every person freely uttered and those “facts” remain gospel in your mind forever. That is, until you start reading and gaining more experience. Some hobbyists never reach a point where they actively start to question some of the statements that appear in books, magazines and in articles on the internet. The real fact is that the hobby of Koi keeping is evolving at a tremendous pace and the more one question the statements made in books etc. that was published many years ago, the faster new ideas will be put into practice. It can only benefit the hobby of Koi keeping. Although some of us have no qualms about trying and evaluating new techniques and products, many have a hard time letting go of old ideas that has been presented to us as fact. Sometimes we are unconsciously hampered by adherence to beliefs in concepts that may or may not have a basis in science or experience, but have been sustained through repetition by some of the more “experienced” Koi keeping community.

These concepts are often presented to the newcomer as Koi dogma, to be accepted without question, but to be treated with great reverence and passed on to those who would follow. If I use the whole capacity of this web-site, there will still not be enough space to incorporate every example of such dogma. At least under this heading it will be possible to highlight some of the great fallacies in koi keeping in a concise way.

Last Updated on Friday, 08 October 2010 16:52