Carole and Ershun Lee also know their koi by name: They can easily pick out Romeo and Juliet from among the 15 fish in their pond, all of which they've raised from infancy.

"They're too expensive to buy when they're larger," Carole Lee says, adding that she gave up trying to learn her koi's Japanese names. "They're hard to pronounce."

Cottam and the Lees will display their different approaches to raising koi on a July 16 pond tour sponsored by the Santa Clara Valley Koi and Water Garden Club. Cottam, who designs and builds koi ponds for a living, is a club member. Carole Lee is club president and her husband handles membership.

Cottam dug his first koi pond in 1964 in the backyard of his parents' home at the request of his mother, an avid gardener. After a 20-year career in the U.S. Air Force, he came back to the Bay Area and earned his general contractor's and landscaper's licenses.

"I've been doing this for 11 years now," Cottam says of his koi pond business. "It's still principally a hobby even though I'm trying to make a [living] at it."

Recently Cottam redesigned the pond at his parents' former home, where he now lives. The new pond holds 5,800 gallons of water and is 7 feet deep to accommodate larger koi. To keep it clean enough for his 12 fish to grow and thrive, Cottam designed and built a system with multiple pumps and filters, hidden by a waterfall and landscaping that includes an azalea bush his mother planted decades ago.

The Lees inherited their 1,500-gallon pond when they moved into their Tangerine Way home 10 years ago. At that time, the water was unfiltered and populated by garden-variety goldfish.

"It was like pea soup," Carole Lee says. "We didn't know how to take care of it."

The Lees joined the koi club and sought advice from Cottam and other members who work in the industry. Carole Lee says she and her husband have benefited from the vast pool of knowledge among the club's 120 members, about 15 percent of whom are Cupertino residents.

"Everyone you ask advice of has a different answer because there's no one right answer," she says.

The Lees say some club members are as interested in the history and lineage of koi as they are in the fish themselves.

"The real diehards know bloodlines and breeders," Ershun Lee says. "We're just hobbyists."

Japanese rice farmers began breeding koi for their aesthetic appeal in the early 1800s. Modern Japanese families keep koi as pets and, since the fish usually live 30 to 50 years, they're often passed down to the next generation.

"In Japan they'd know the lineage of a fish just by looking at it," Cottam says. "They can go back 10 generations."

The Lees are more interested in having their koi eat out of their hands than in figuring out who spawned them.

"It's very restful to watch them," Carole Lee says. "We like the sound of the water."

Cottam says his backyard waterfall drowns out the noise from nearby Highway 101, making for a meditative setting.

"I like coming out [to the koi pond] when the moon is full," he says. "You can see the fish but not the water. It's like they're floating on air."

The Santa Clara Valley Koi and Water Garden Club hosts its annual pond tour on July 16, 9 a.m.-4 p.m. Tickets and maps are available at all ponds on the tour, and docents will be on hand. Tickets are $10 for adults and $5 for teens; admission is free for children under age 10. For more information, visit www.sckoi.com or call 650.969.0715.