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Many frog species are edible, but in the U.S. the American bullfrog Rana catesbeiana has long been considered the most suitable for production. In the 1970s and 1980s considerable research was conducted to develop commercial methods for bullfrog production. Subsequently, management and husbandry practices were adapted to allow continuous bullfrog production in tropical climates, but several major problems with American bullfrog culture have never been solved completely. These factors have severely limited commercial production of this species, even in tropical regions with suitable temperatures for year-round growth.
When combined with comparatively high land and labor costs and limited growing seasons, these constraints have effectively prevented the development of commercially viable frog aquaculture in the United States. Competition from imports of wild-harvested frogs has kept market prices well below the cost of production for would-be frog producers in the U.S. Additionally, the rapid development of culture methods for Asian species that consume commercial pelleted diets and are more suited to captivity may result in even more imported product in the U.S. marketplace in the coming years.
Approaches to bullfrog culture that have been tried over the years include semi-natural systems, controlled artificial pond systems, and indoor laboratory culture. Semi-natural systems often consist of little more than earthen ponds with enclosures to keep frogs in and predators out. These systems usually have major problems with predation, cannibalism, diseases, limited food sources, water quality/sanitation, and fluctuating temperatures. Artificial systems also have problems with cannibalism and diseases, as well as inadequate nutrition because few alternatives to live feed are available and the American bullfrog only eats prey (or artificial feed) that it perceives to be living and moving.
Bullfrog production requires special facilities and culture practices for various life stages, including egg incubation, tadpole culture, grow-out of young frogs, and maintenance and breeding of adult broodstock. For all life stages, the most important day-to-day management consideration is adequate sanitation to prevent bacterial diseases. Each stage of the life cycle also requires sanitary and nutritionally complete food supplies.
Bullfrog broodstock are maintained in specially designed facilities, where eggs are collected daily. Eggs are incubated in hatchery tanks and hatch into larval tadpoles after 4 to 5 days depending on temperature. Roughly three weeks after hatching tadpoles are transferred to rearing ponds. Various diets have been used successfully to rear tadpoles to metamorphosis, which begins around five weeks after stocking in rearing ponds. Metamorphosed frogs are then transferred to grow-out pens, constructed of artificial materials, such as pond liner, that can be cleaned and disinfected daily. Feed consists of live fish, smaller tadpoles, crustaceans, and other living prey. Methods to support large-scale commercial grow-out using artificial diets with the American bullfrog are not well-documented or easily replicated. It may be necessary to sort frogs by size at least once during the grow-out period to reduce losses to cannibalism.
In the southeastern U.S., the most suitable region for commercial frog production in the country, bullfrog aquaculture is limited by technical and labor requirements, a short growing season and unsolved disease and nutritional problems. If planning a frog farming facility it will be necessary to calculate the productive capacity of the system in order to estimate capital costs, projected production, revenues and input requirements. At this point, an evaluation can begin in order to determine if the operation will be large enough to generate profits and if so, a market analysis can be undertaken.
Prospective producers should keep in mind that frog farming may require special permits and/or licenses in some states. If frogs will be partially or completely dressed and processed, permits and licenses will be required. If they will be sold to live markets, such as are available in many Asian ethnic communities, most states will require licenses and record-keeping to differentiate farmed products from wild-caught frogs.
The American bullfrog was widely introduced to distant lands over the last century, primarily with an eye toward farming or as a substitute for smaller native species. It is now found in more than 40 countries, and is being cultured primarily in South America and Asia. However, many governments, researchers and entrepreneurs across the world have focused on developing culture techniques for native frog species. As interest in frog farming spread throughout Asia, researchers found that the live or moving feed problem could be avoided altogether with some species. The tiger frog (Hoplobatrachus ragulosus) eagerly feeds on pellets without any need to move them about mechanically. While this species is still referred to by several scientific names, it has emerged as the most adaptable frog for farming in Asia. Many large feed milling companies throughout Asia now produce frog feeds, specifically formulated for tiger frog grow-out.
Small scale, “backyard” frog farms still appear to be the norm in most Asian countries, suggesting that management practices and value chains have not yet reached the point where significant economies of scale come into play, but this is beginning to change. In 2017 the Chinese Academy of Engineering estimated the value of the country’s frog farming industry was worth over US $7 billion, and as frog production continues to grow across the Asian continent supplies will become more and more available to U.S. markets.
- Commercial Frog Farming. https://vtechworks.lib.vt.edu/bitstream/handle/10919/48949/420-255_pdf.pdf Virginia Tech Cooperative Extension.
- Frog Farming Facts. https://mdc.mo.gov/improve-your-property/habitat-management/pond-and-stream-management/ponds-fish-frog-management/frog Missouri Department of Conservation.
- The Giant Frog Farms of the 1930s… https://www.atlasobscura.com/articles/frog-farming-1930s-failure-ponds-canning-legs-conservation Sarah Laskow, Atlas Obscura.
- Bullfrog Culture. https://srac.tamu.edu/fact-sheets/serve/96 Southern Regional Aquaculture Center.
- Amphibious aquaculture: why frog farming is set for success. https://thefishsite.com/articles/amphibious-aquaculture-why-frog-farming-is-set-for-success The Fish Site.
Prepared by C. Greg Lutz, Louisiana State University Agricultural Center