Okay, so you're not a big goldfish fan. It happens. But you can still keep fish in your water garden, and you can do it with koi.

Originally wild carp that were bred over the years by the Imperial Chinese and, later, exported to Japan and around the world, koi range in price from only a few dollars to several thousand dollars or more.

The most important factor in valuing a koi is its size. As with a Sumo wrestler, the bigger the koi, the more valuable it is. When buying baby koi, look for the ones with the largest heads, assuming that a big head eventually begets a big body.

Conformation, or overall body shape, also plays a role in valuing a koi. The most valuable shape is described as "torpedo-like." If you find a koi that looks as if it could be shot out of the forward tube of a submarine, grab it. It’s a winner!

Finally, skin quality, color intensity, and clarity also count when valuing a koi. Experts check closely in order to spot any blemishes or flaws in the skin of the fish. They also consider color intensity, balance, and clarity of the pattern on the koi, seeking fish with clearly marked color delineations.

General Koi Categories
There are three commonly accepted categories of koi. These categories include, from bottom to top, Pond Quality; Ornamental Quality; and Show Quality.

1. Pond Quality. The most common and least expensive, these include fish sold by local pet shops and some breeders. Pond koi are usually locally bred, have mixed bloodlines, have no papers that distinguish them, and are not suitable for competition. They are, however, inexpensive and can be every bit as endearing as ornamental or show quality koi.

2. Ornamental Quality are the next most common and moderately expensive koi. Most are bred from good quality parents, have good blood lines, good conformation, and beautiful coloring. The differences between ornamental and show koi are found in the pattern, the body conformation, the skin quality, and the evenness of color. Most ornamental Koi have unbalanced patterns with “flaws” in their skin, coloring, and shape.

3. Show Quality, the least common and most expensive, koi are expected to have good blood lines, good body conformation, shiny unflawed skin, and balanced patterns with crisp edges. Experts consider bloodline to be such an important factor that they almost always take for granted that show quality koi have come from show quality parents. Fewer than 1 percent of all koi owners own or care about owning show quality koi, making this variety of koi that much rarer and driving the prices even higher.

Koi Families
Nearly 95 percent of all koi in the world fall into one of five categories. Three of these categories are collectively known as Gosanke (in Japanese, three families). The Big Three are comprised of Kohaku, Sanke, and Showa.

The Kohaku is a unique white Koi with red markings. Just as with fingerprints and snowflakes, no two are alike. Various sub-categories of Kohaku refer to differing patterns of red on white. When talking about koi, Kohaku is inevitably at the top of the list.

Back in the early 1900's, a second variety of koi emerged. It added some unique black markings to the red and white of the Kohaku. This breed is called the Sanke or Sanshoku, the second of the three families.

Then, during the 1930's, a third breed was developed and introduced to the market. It features red and white markings contrasted against a jet-black base. The new breed is known as Showa. In keeping with tradition, its color intensity, clarity, and crispness of pattern all play major roles in the valuation of the breed. Showa represents the third member of The Big Three.

The fourth breed is the most popular in America. It's known as Hikarimujil, which means "light without pattern." The light part of the name refers to a bright, metallic sheen that characterizes this category. Hikarimujil are singular in color, meaning they are "without pattern." Hikarimujil can be jet-black, green, red, yellow, blue, or gold. All lack any type of pattern and have only one color, which makes them unique among koi.

The final breed is known as the Kawarigoi, which translated means “changing,” or "different" koi. Into this category fall all the varieties both named and unnamed that either have unstable characteristics or do not fit into any other recognized category.

As you may well imagine, this category contains literally hundreds of different examples and provides an all-inclusive category for anything new that might come along. Ranging from spectacular to bizarre, the Kawarigoi are what Westerners would consider mutts or strays, even though numerous champions have come from this category.