For Mortgages Underwater, Help Swims In

ANTIOCH, Calif. -- While lawmakers in Washington struggle to solve the nation's foreclosure crisis, officials here are using a small fish to clean up some of the mess.

The Gambusia affinis is commonly known as the "mosquito fish" because of its healthy appetite for the larvae of the irritating and disease-spreading insects. Lately, the fish is being pressed into service in California, Arizona, Florida and other areas struggling with a soaring number of foreclosures.

The problem: swimming pools of abandoned homes have turned into mosquito breeding grounds.

"They are real heroes," says Josefa Cabada, a technician at the Contra Costa Mosquito & Vector Control District, a government agency. "I've never seen a mosquito in a pool with mosquito fish."

The mosquito fish is well suited for a prolonged housing slump. Hardy creatures with big appetites, they can survive in oxygen-depleted swimming pools for many months, eating up to 500 larvae a day and giving birth to 60 fry a month. That can save environmental crews from having to repeatedly spray pesticides in the pools while the houses grind through the foreclosure process.

Some local agencies, increasingly worried about mosquito-borne diseases like the West Nile Virus, are taking to the air to find problem swimming pools. The Turlock Abatement District, near Modesto, Calif., last month hired a plane to fly over 55 square miles, snapping pictures of pools from about 5,000 feet. On the ground, mosquito-control crews cross-referenced properties that had greenish-brown pools with a street map and a database of local foreclosed homes.

A significant threat to public health can be resolved through the use of a biological intervention. Learn more about the fish that eats mosquito larvae to reduce the threat of the west nile virus. WSJ's Michael Corkery reports. (May 8)

In the Turlock district alone, about 475 stagnant pools were identified on the flyover. Many of those will be filled with mosquito fish.

To deploy the fish, communities are turning to workers like Ms. Cabada, a former Navy sailor. She has raised pet fish since she was a girl and keeps a 55-gallon aquarium at home along with her five love birds, two dogs, two pet pigeons and a rooster. Many mornings, she collects hundreds of fish, housed in massive bubbling tanks at mosquito-control headquarters, and transports them to pools and other water sources in a cooler in the back of her pickup truck. In the sweltering heat, the fish ride up front.

"They're my buddies for the day,'' Ms. Cabada says.

After Hurricane Katrina

The fish have been used to keep mosquito populations down for many decades by farmers and environmental crews who stock them in cattle ponds, irrigation ditches and decorative ponds. In the aftermath of Hurricane Katrina, mosquito fish were stocked in the thousands of swimming pools abandoned around New Orleans in the storm.

Native to the Gulf Coast states, the mosquito fish have mouths shaped to slurp larvae off the water's surface like noodles. The females can grow up to 3 inches long, and reproduce quickly. Technicians in Contra Costa typically release about 150 fish into each pool. Within weeks, the pools teem with a thousand of the scaly, gray predators.

When Ms. Cabada released fish into a pool behind a vacant home one recent day, they darted and dove through the water, which was the color of herbal tea. "It comforts you just to see them swimming around," she says.

Located along the delta where the Sacramento River meets the salt waters of the San Francisco Bay area, Contra Costa County's warm climate makes for prime mosquito country. The area is also struggling with foreclosures. Default notices more than doubled to 4,718 in the first quarter from the previous year, according to the research firm, DataQuick Information Systems.

Turlock Mosquito Abatement District

But like everything else about the housing crisis, the fish aren't a perfect fix. They baffle some bankers and agents hired by lenders to look after the vacant homes, says Carlos Sanabria, the Contra Costa mosquito control district's operations manager. "People think some trout-size thing is going to be swimming around in there clogging up the vents," he says. "I explain it's not something you are going to have for dinner."

Not everybody likes turning swimming pools into giant aquariums. "First you have fish, then you have birds that eat them" and then bird droppings, says Arnie Shal, a retired accountant, who lives next to several foreclosed houses with pools in Clearwater, Fla. "It's not really a healthy situation."

Mr. Shal, 71 years old, recently protested the use of mosquito fish in his posh development to the neighborhood association. He fears the fish will die in the Florida heat and allow mosquitoes to breed out of control. "This is trying to fix a serious health issue on the cheap," he says, "Everyone is under budgetary pressure, I understand. But they are going to leave us bug infested."

There are other concerns. A 1999 study showed that when biologists introduced mosquito fish to a pond containing tadpoles of the California red-legged frog, which is a threatened species, the fish harassed the tadpoles and harmed their growth. The frogs that emerged from the pond were 30% smaller than frogs raised in a pond without mosquito fish.

Stubby Tadpoles

"The Gambusia just keep taking bites out of the tadpoles, and the tadpoles end up kind of stubby," says the study's author, Sharon Lawler, a professor of entomology at University of California at Davis. She says well-intentioned buyers of foreclosed houses should be cautioned not to transfer the Gambusia from a pool into a pond containing the fragile tadpoles.

In addition to raising fish, Contra Costa scientists keep an indoor colony of mosquitoes for research. It falls to the district's entomologist, Steve Schutz, to provide the insects with their regular "blood meal," which he says the females need in order to reproduce. Every week or so, he sticks his arm into a screened cage containing more than a hundred mosquitoes in a hot and humid room called the "insectary."

He usually reads a book or works on a puzzle while the mosquitoes bite him for about 20 minutes. "I have been doing it so long that it doesn't even itch that much,'' he says. The district used to use a bobwhite quail for the blood meal, but Mr. Schutz says it's less hassle to offer up his arm.

'It's Organic'

It can take months after a defaulted homeowner leaves a house before the banks start caring for the property, Mr. Sanabria says. During that time, the fish can contain the mosquito problem, while a bank hires a caretaker to drain the pool or restart the filtration system. The fish are more environmentally friendly than constant spraying with pesticides. One problem with putting a cover on the pool is that the cover's exterior can collect water and breed mosquitoes, if left unchecked.

"This is how we are supposed to take care of things,'' says Robert Kloepping, who lives next to a vacant home with a pool containing mosquito fish in Antioch, Calif. "I think it's cool, man. It's organic."

The fish face a bleak future once they've done their job. Some begin eating each other after they run out of mosquito larvae. When the houses are sold, new owners can collect the fish and return them to the mosquito-control agency. In some cases, the environmental services department in Maricopa County, Arizona offers to come back and round up the fish it dumped in pools. But most fish will probably die as home owners drain the pools or begin treating them so they can swim in them.

"That's part of the program,'' says Chris Miller, a biologist at the Contra Costa mosquito and vector control district. "They are sacrificial."

Write to Michael Corkery at michael.corkery@wsj.com

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