For James Kinney, president of the Aloha Koi Appreciation Society, keeping a koi fish pond in ecological balance brings a sense of peace.

"It’s a living art form," he said. "It’s the beauty and the peacefulness. I can’t pinpoint one thing, but there are many facets of the hobby that keep us hooked."

The society’s fourth annual International Aloha Koi Show competition and auction takes place this weekend at the Waikiki Aquarium, attracting both local and out-of-state participants.

In his yard, Kinney has 43 koi in a specially built, 50,000-gallon pond about the size of a large swimming pool. It’s 5 1/2 -feet deep, with a pedestrian bridge and surrounded by bonsai trees.

When he comes home, it’s relaxing to feed his koi and watch them swim, he said.

Kinney, who has taken home the title of grand champion several times, considers his fish as pets. All 43 have names and individual personalities, he said.

Koi fish — called nishikigoi in Japan — are domesticated varieties of the common carp. In Japanese, nishikigoi means "brocaded carp," alluding to its extravagant covering of lustrous scales.

Black carp were initially grown by Japanese farmers in Niigata for food during the winter, but after regular breeding, various color combinations began to emerge. The fish, often referred to as "living jewels," became prized for their ornamental beauty.

Koi come in combinations of white, orange, black, red, yellow, blue, cream and silver.

The varieties are based on colors and pattern: for example, kohaku (red pattern on white), chagoi (olive or brown), asagi (indigo or blue), tancho (solid-colored body with a red spot on the head) and showa (a calligraphic sumi pattern on a kohaku).

Today, hobbyists all over the world keep koi fish, which are symbolic of peace, longevity and love.

Kinney’s fish Bheula, a chagoi, measures about 40 inches long and 34 inches around.

She’s still growing and is showing great potential, he said. Sparkles, with metallic orange, white, and black scales, is a mature grand champion.

Most of the koi on Oahu come from the Kodama Koi Farm, which is organizing this weekend’s show. The 10-acre farm in Mililani imports its fish from Japan and is one of the largest koi farms in the United States, according to company President Taro Kodama.

Koi fish have an average life span of 70 to 80 years, said Kodama, although there are records of a koi that lived more than 200 years.

They range in length between 2 to 40 inches, depending on age and living environment. Prices start at $30 per fish but can soar to $25,000 for the most prized specimens.

Kodama said Hawaii is an ideal place to raise koi due to the quality of the island water and year-round warm weather. A number of mainland koi owners "board" their prized fish at the farm for those reasons.

Koi can be kept in a large aquarium, a small pond, or even a home-built wood encasement lined with rubber, he said. For a small pond, a minimum depth of 4 1/2 feet is recommended, along with a good filtration system.

Since koi are social, Kodama recommends starting with at least four or five.

At the competition, the fish will be judged on several criteria, including bloodline, body conformation (fullness and roundness), quality of skin and color. Larger is generally considered better. Titles will be awarded for best in size, best of variety, baby champion, young champion, mature champion, best jumbo, and overall grand champion.

An expert from Japan will select the winners, who get trophies and bragging rights, but no cash prize.

"The true reason we show our koi is to share the art," Kinney said. "It’s also a chance to see other people’s koi."