That Reptile Blog – Reptile, Amphibian and Exotic Pet Care and Information

The robust African bullfrog shares with the fire salamander and Chinese/Japanese giant salamanders the distinction of being the longest lived of all captive amphibians. I personally know of 2 specimens that lived for 21 years in captivity, both owned by the same person (interestingly, although housed separately, they died within a few days of one other). The unpublished longevity record for the species is 50 years.

Ammonia – an Ever-Present Threat
However, one easily-overlooked point – terrarium hygiene – can very quickly end their potentially long lives. In my experience, a lack of attention to this critical point is the most common cause of African bullfrog deaths in captivity. Despite their burly, somewhat tank-like exteriors, African bullfrogs are extremely sensitive to ammonia toxicity…tiny metamorphs and huge, decades-old adults are equally vulnerable.

These frogs usually (but absolutely not “always”!) defecate in their water bowl. The bowl should be cleaned at least once daily, even if it does not appear fouled. Frogs soaking in fouled water will absorb ammonia through their skin and can die in short order.

Daily care while you are on vacation or otherwise absent from home is a must…a day or so of missed cleanings can easily kill a treasured old pet (think of how you’d feel then!).

Useful Products and Techniques
R-Zilla Terrarium Cleaner is safe to use on water bowls and terrariums, but wherever amphibians are concerned it is essential that all surfaces are rinsed thoroughly after being disinfected. Be sure to use a water conditioner  to de-chlorinate water used in the bowl and in spraying the substrate.

A very useful product of which I was made aware recently is Hagen Cycle. It is contains huge populations of live beneficial aerobic bacteria, is being increasingly used in laboratory frog colonies, both for aquatic species and in the water bowls of others. I believe it is an important product to consider when keeping large frogs, which produce copious amounts of nitrogenous wastes (it is not, however, a substitute for water changes).

As your frog may also defecate outside of the water bowl, it is important that the entire terrarium can be easily cleaned. Simple set-ups are therefore preferable for African bullfrogs (when designing planted zoo exhibits, I always allow for a floor drain and false bottom, so that the substrate can be hosed down without removing the frog). Washable terrarium liners are very useful in African bullfrog enclosures.

Further Reading
You can read more about African bullfrog natural history and captive husbandry in the following articles on this blog: The African Bullfrog – Devoted Parent, An Appetite for Cobras , and Feeding African Bullfrogs.

See Feeding Pet African Bullfrogs Pyxicephalus adspersus – Part 1 for the first part of this article.

How does one satisfy a 9 pound amphibian!?

Wild-Caught Insects
Native invertebrates, collected from pesticide-free areas, should be offered whenever possible. In my work with frogs of all types, I’ve found very little that approaches the beneficial effects of a varied diet. Zoo Med’s Bug Napper is an excellent insect trap.

Sweeping a net through tall grass and searching around outdoor lights will also yield a number of useful species. Avoid using spiders, stinging and brightly-colored insects and fireflies, and do not collect during times when your collecting site is being sprayed with insecticides as part of mosquito control programs.

African bullfrogs under my care have enthusiastically accepted (“enthusiastically” goes without saying where these stout fellows are concerned!) cicadas, katydids, grasshoppers, beetles and their grubs, moths, tree crickets, hover flies, caterpillars, and most everything else I could come up with. I rely heavily upon wild-caught invertebrates throughout the spring, summer and early fall, but even a few beetles plucked from a screen door every night or so will go a long way in keeping your pet in the peak of health.

The Importance of Canned Insects
African bullfrogs can be easily trained to accept non-living food items from a plastic feeding tongs (well, to be honest, no actual “training” is involved…they generally just swallow whatever moves within range!). They have a very vigorous feeding response, and hit food quite hard. Accordingly, I avoid using metal feeding implements, as the risk of a mouth injury is fairly high.

This frog’s willingness to tong-feed is quite fortunate, because it enables us to use canned insects as a source of important dietary variety. The canned grasshoppers are quite large, and are suitable even for adult African bullfrogs. Large canned grasshoppers, silkworms and other insects can be broken into smaller pieces for juvenile frogs.

Meal Frequency and Nutritional Supplements
Juvenile frogs can be fed 3-4 times weekly, while adults do fine with a meal each 4-7 days (fast them for 10 days or so after a “heavy” meal of large shiners or pink mice). Smaller, more frequent meals can also be offered…I personally find this preferable, but it is not as critical for with this species as it seems to be for certain others.

The food of juveniles should be powdered with Reptocal at every other feeding, that of adults once weekly. During periods when you are unable to offer a varied diet, alternate Reptocal with Reptivite.

The African bullfrog pictured here may be seen in the wonderful amphibian exhibit area at Norwalk Connecticut’s Maritime Aquarium. I was involved in the project’s development as a consultant, and am pleased to say that the staff has done an excellent job of keeping and breeding a wide variety of amphibians in beautiful, naturalistic exhibits. The accompanying photographs show some of the aquarium’s other residents – albino American bullfrogs with pumpkinseed sunfishes, poison frogs and tiger salamanders. Also exhibited are barking treefrogs, Surinam toads, bronze frogs, mudpuppies, fire salamanders, red-eyed treefrogs and many other toads, salamanders and frogs from both the USA and abroad – please visit if you have the opportunity.

Further Reading
For a startling account of African bullfrog predation upon red spitting cobras and of the amazing degree of parental care these frogs provide to their tadpoles, please see my articles “An Appetite for Cobras” and “The African Bullfrog (South African Burrowing Frog, Giant Bullfrog), Pyxicephalus adspersus: The World’s Heaviest Frog is also a Devoted Parent”.

African bullfrogs seem to give rise to all sorts of interesting stories.

How does one satisfy a 9 pound amphibian!?”

Although African bullfrogs are among the most popular and long-lived (to 50 years) of amphibian pets, there remains some confusion as to their proper diet in captivity. Prompted by recent blog inquiries, I thought I’d set down a few thoughts on the subject.

Calcium Through Cannibalism
African bullfrogs, especially growing animals, seem to require a great deal of calcium. Perhaps this is due to their naturally fast growth rate – in their native southern Africa, breeding ponds dry quickly and tadpoles must transform quickly if they are to survive. The froglets then have but a short time to gorge upon enough food to sustain themselves through aestivation periods (dry weather dormancy) that may reach a year in length.

Often, the main source of food for the small metamorphs (transforming frogs) is other African bullfrogs. There is evidence that frogs will preferentially prey upon unrelated individuals, but in any case a diet so high in vertebrates is quite unusual for amphibians.

The Perils of a Rodent-Based Diet
Captive amphibians that are fed vertebrate-rich diets, usually in the form of mice, often develop eye (lipid deposits), kidney and liver problems. Although African bullfrogs do feed heavily upon other frogs in the wild, the practice of feeding captives largely upon mice, while a convenient way of sating these huge fellows, is not advisable.

Outside of the breeding season, the diet in the wild consists mainly of locusts, spiders, beetles, scorpions and other invertebrates…the vertebrates that are taken are more likely to be lizards, snakes and frogs than mammals. In some cases, rodent-based captive diets have not led to problems, but hair impactions and obesity-related health complications have resulted in others.

Providing a Healthful, Varied Diet

Fish and Crayfish
I prefer using goldfish, minnows and shiners for the vertebrate portion of African bullfrog diets, (the bones are an excellent calcium source), with only an occasional pink (un-furred mouse) being provided. Crayfishes, if available, are a fine food item and good calcium source. Neither of these food items is likely encountered by African bullfrogs in their native habitat – crayfish are not native to Africa, although 1 North American species is introduced, and the frogs tend to breed in fishless, temporary pools – but both have proven very useful in the long-term maintenance of this species.

Earthworms and Nightcrawlers
Earthworms, including nightcrawlers for adult frogs, are an excellent source of nutrition, and can comprise a majority of the food offered. The earthworm’s calcium: phosphorus ratio has been shown to generally hover around 2:1, which is ideal as regards frog diets. I believe that earthworms from different habitats may vary in this regard, but have none-the-less had very good results with earthworm-based diets over many years.

Commercially Available Insects
The balance of the diet can consist of crickets, roaches, super mealworms, waxworms, tomato hornworms and other commercially available insects. Large roaches (as well as nightcrawlers) present an excellent means of keeping your frog sated without resorting to rodents. For information on keeping and breeding the orange-spotted roach, please see my article “The Orange (or Guyana) Spotted Roach, Blaptica dubia.

Read Feeding Pet African Bullfrogs Pyxicephalus adspersus – Part 2

Those who keep or observe frogs soon learn of their prodigious appetites. Surely the champion Anuran eater must be the African bullfrog, Pyxicephalus adspersus. Native to southern Africa, this brute is a popular pet, and with good reason – captive longevity is said to approach 50 years. Two animals that I know of, kept in separate enclosures by the same person, both expired at age 21, in the same week.

The most memorable “frog-eating footage” I’ve seen focused on African bullfrogs in the Etosha Pan, northern Namibia. One enormous animal swallowed a centipede of at least 10 inches in length, which bit the frog numerous times on the way down. Another frog latched onto an emperor scorpion, which also did its best to make itself a “memorable” meal. But a note I read in an African nature journal tops all – a huge male frog burrowed into an outdoor cage at a South African snake park and was, when discovered, in the process of swallowing his 17th baby spitting cobra!

All of this eating results, as you might imagine, in frogs of impressive proportions – a male at the Fort Worth Zoo measured 10 inches from snout to vent and 9 ¾ inches around – a near perfect circle! His weight surely topped 5 pounds, but I do not have the exact figure.

Our own American bullfrog, Rana (Lithobates) catesbeianus, offers its African cousin some competition. While working at the Bronx Zoo, it became my habit to toss crickets to the bullfrogs that had colonized a small artificial pond. The frogs became bold in time, and visitors enjoyed the show. On one occasion a bullfrog’s leap for food brought it directly in front of another. The larger animal grabbed the smaller, who was fully three quarters his size and, in front of 50 or so second-graders, proceeded to jam the squirming neighbor down his massive gullet. I observed this fellow thereafter – his noticeably distended abdomen flattened out in two days, after which he again gobbled crickets with enthusiasm!

Male African bullfrogs are diligent parents – they defend the eggs and dig channels to bring water to their tadpoles. You can learn more at:
http://www.amphibiaweb.org/