TWIN FALLS • Sixteen-year-old Zoe Rivas has a weekend job that none of her classmates can match.
She was hard at work again Sunday morning, measuring and weighing 145 bullfrogs to the nearest centimeter and gram in preparation for shipping them to buyers. Zoe, her mother, Lisa, and father, Steve, run the Rana Ranch commercial bullfrog operation in the Twin Falls area.
“She’s very central to our business,” Steve Rivas said of his daughter. “It’s definitely a family business.”
He works full-time as an instructor in the College of Southern Idaho’s aquaculture program, and operates Rana Ranch as a sideline. He and Lisa visit the ponds on a one-tenth-acre site every weekday at 5:30 a.m. to clean the facilities and feed the frogs.
The family sells 6,000 frogs annually to about three dozen regular customers, almost all of them outside Idaho. Most frogs go to universities and government agencies, although a few are used to stock ponds.
“These animals have a lot of applications to human health,” Steve Rivas said, adding they are used in heart, cancer and Alzheimer’s disease studies. “These protect a lot of other frogs from being used in research. I feel that’s better than depleting the wild resource.”
In addition, wild frogs often have pathogens that make them unsuitable for research.
Steve Rivas said he’s always been interested in amphibians. The Rivases began raising the animals in 1994, three years after Steve Rivas graduated from the technical aquaculture program at CSI.
He calls bullfrogs good farm animals because their metabolism and growth can be regulated by temperature. That helps produce frogs to the exact size and weight that his customers demand.
The Magic Valley’s high-quality water — warm or cold as needed — is key to producing good frogs, Steve Rivas said. “We can regulate the temperature to what we need for various life stages.”
He added that Rana Ranch is an example of sustainable agriculture with no herbicides, pesticides, inorganic fertilizers or electricity used.
“The manure is composted and the effluent water is used for irrigation,” he said. “Rana Ranch has no debt and has never accepted any public funding.”
The frogs are sold in four sizes, from body lengths of up to 4 inches all the way to “super jumbo” versions longer than 5 inches and weighing more than two-thirds of a pound.
A local mill makes the grain-based pellet feed that includes animal proteins. Steve said the frogs must be fed every day or they will start eating each other.
Zoe Rivas said even the family dog helps out with the business.
“If a frog escapes, Dottie goes after it,” she said. “She gently holds it in her mouth.”
About a half-dozen pens separate the animals by age, starting with tadpoles.
Steve Rivas said the family prefers to keep their business a part-time endeavor.
“There are a lot of niche farms in the Magic Valley,” he said.