Though very often an expensive and vexing hobby, keeping koi is also very relaxing, beautiful, enviable and the hobby of a lifetime. Many people who invest in koi find they catch a fever of excitement that leads them to keep trying to find that perfect fish.

Not surprisingly fanciers range from the most simple of backyard ponds to tens of thousands of litre ponds with hundreds of fish and breeding programs. The fact that very well conforming specimens can fetch thousands and thousands of dollars is not surprising.

For the backyard koi keeper, however, simply having a good reason to have a waterfall might be enough. There is no right or wrong reason, only the desire of all to have healthy and happy fish.

There are over a hundred different types of koi registered for show in professional breeder and amateur clubs throughout Japan and the world, though new varieties are still largely shown in Japan.

Koi may be generally grouped according to and in combinations of:

skin colour skin pattern scale pattern

Whichever you consider most important or if you have your heart set on a very particular fish, there is one for every taste. In more than 16 categories, now, there are over a hundred types of koi and an infinity of variety in each type.

True koi are always judged from from above, and their ponds are designed to facilitate this. From this angle, one judges the conformity and harmony of the design depending upon which type of koi you're looking at. That said, some characteristics are considered from the side such as the markings on the eyes and and cheeks.

On the other hand, many people who keep koi hybrids choose to view them from the side as well, especially those with unusual fins or scale patterns. Koi purists do not consider these actual koi.

There were once only a few colours, but with the pace of breeding development (and the financial incentive to do so) several new colours have emerged in the last 30 years with the injection of new material. These colours are arranged in in a seemingly infinite variety of combinations.

Markings are judged from above in special, bright blue pools that set off the bright, metallic colours. Outside of Japan the colours are known by their names in Japanese as well as the local language, since so much of the literature is translated from the original Japanese. For instance, colours include:

Ai - blue Aka / Hi - red, though actually a rather dark orange that can vary somewhat Asagi - light blue (a greyish/silvery blue) Ki - non-metallic yellow Orengi - orange Shiro - white Sumi - dark black (sometimes called "india ink")

They tend to have something of a metallic sheen unless otherwise noted. Generally these distinctions apply across the board and describe both underlying and overlaid colours. Additionally, there are a few distinct colour patterns that have special names:

Kohaku - red and white only Ogon - one colour only Sanshoku - any three colours regardless of the shape of the coloured areas

Just about any koi can be classified into one of the many types. However, most fish you'll be looking at as a first time koi buyer fall into a few basic categories. Many of the fish sold in the US and EU are those who've been rejected from breeding programs that are in continual pursuit of the perfect koi. Just because it doesn't conform to the accepted standard of show beauty doesn't mean they are not unique and beautiful.