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

Frogs that are clad in yellow, orange, and red, such as Fire-Bellied Toads and Red-Eyed Treefrogs, often become somewhat dull in coloration after a time in captivity. I’ve noticed this in a variety of species under my care in zoos and at home, yet the phenomenon is rare in the wild or among animals kept outdoors under semi-natural conditions. Color loss can also indicate a health concern (please see below), but often the affected animals are robust and doing well. A photograph showing an astonishing difference in coloration between Red-Eyed Treefrogs maintained on 2 different diets recently caught my eye, and I thought it might be useful to summarize the related research here.

Acquiring Color: Why are Red Frogs Red?

Pigments known as carotenoids are responsible for most of the orange, red and yellow coloration exhibited by frogs. Color is important not just from an aesthetic point of view (or a monetary one, for those who breed “designer frogs”!) but may also affect breeding success and the ability to hide from or deter predators.

In addition to these roles, carotenoids also act as antioxidants and function in the immune and other systems. Carotenoids are manufactured by plants, bacteria and fungi; frogs and other vertebrates must obtain them from their diet.

Improving the Carotenoid Content of Feeder Insects

Researchers at the University of Manchester and the Chester Zoo investigated carotenoid levels in three species of crickets and three different cricket diets (Zooquaria, No. 5, p.6). One of those studied, the Domestic or House Cricket, Acheta domesticus, is used for pet food in the USA. The others – the Tropical House Cricket, Gryllodes sigillatus, and the Mediterranean Field Cricket, Gryllus bimaculatus – are more commonly seen in European and Asian collections.   A diet comprised of fruits and vegetables provided crickets with the highest carotenoid levels. A tropical fish food (flakes) diet resulted in intermediate carotenoid levels, and the lowest levels were seen in crickets feeding upon wheat germ and other grains.   Mediterranean Field Crickets achieved higher concentrations than did the other species, but none retained carotenoids for very long. Carotenoid levels plummeted within 48 hours, so gut-loaded crickets should be used within a day or so after consuming fruits, vegetables and other carotenoid rich foods; please see the article linked below for further information.

Future Research

Although the study was spurred by an interest in the effect of carotenoids on the immune system, the coloration aspect is starting to attract attention (please see photos of red-eyed treefrogs here). Further study is needed, but it’s clear that adding fruits and vegetables to the diets we provide crickets, roaches and other feeders makes good sense. Bear in mind also that this study looked at one aspect of diet…fresh produce no doubt offers a wide variety of other health benefits.   As a novice bird keeper long ago, I learned that flamingos denied sufficient shrimp and canthaxanthin soon “bleach-out”…today we still know far more about this topic as it relates to birds than to amphibians. But some of that knowledge may have applicability to herps – in any event, I hope that more private keepers and researchers will take an interest. I’ll stay alert for updates; in the meantime, please post any relevant thoughts and links below, thanks.

Further Reading

Nutritious Foods for Frogs and Toads Cricket Nutrient Level Study Cricket Care and Feeding

Frog owners have recently been presented with an interesting alternative to live insects and rodents as a pet food source. Continuing its trend of pioneering innovative, well-researched products, Zoo Med has introduced a powdered food that can be molded into various sizes and tong-fed to frogs. Although long-term studies on the value of commercial diets are lacking, experience indicates that some prepared/artificial diets have proven very useful. For example, thousands of generations of Mexican Axolotls have been bred (in research labs) on beef liver alone, African Clawed Frogs and many newts do well on Reptomin-based diets, and trout chow seems useful for American Bullfrogs. In both in zoos and my own collection, I have raised Mexican Axolotls and various newts, salamander larvae, and tadpoles primarily on trout chow and Reptomin. Zoo Med’s Pacman Food is eagerly accepted by African Bull and Horned Frogs (no surprises there -please see video below!) and Marine Toads. It’s likely that other “bold” amphibians, such as White’s Treefrogs, Fire Salamanders, American Toads, would be willing give this untraditional food a try as well.

 

Why Consider a Prepared Diet?

Usually, commercial diets are promoted for convenience-sake and as an option for pet owners who do not wish to handle live insects or rodents. However, I’m mainly interested in Zoo Med’s Pacman Frog Food because it may help to solve 2 recurring problems faced by frog owners. The first is the difficulty in providing adequate dietary variety. Wild amphibians utilize dozens to hundreds of species as food, but most pets must make do with 2-3 food items at best. Owners of African Bullfrogs, Horned Frogs, Cane Toads and other giants face the additional task of “filling-up” their pets and providing enough calcium without over-using rodents (while some success has been had on

mouse-based diets, there are also risks…please see this article).

 

Providing enough high-quality food can be a major undertaking – please see the article linked below to read about an African Bullfrog caught in the act of swallowing 17 baby cobras! Zoo Med’s product, which one mixes with a bit of water, can be molded into any size (or shape!), and so might be useful to people keeping dinner-plate sized amphibian behemoths.

 

Some Considerations

We do not have studies illustrating benefits or problems associated with this food; long-term success is claimed by a Japanese company manufacturing a related product. The examples I mentioned earlier (amphibians fed dry foods, liver, etc.) may be somewhat relevant, but we cannot draw any direct conclusions about Horned Frogs or others from these.

 

I would suggest trying Zoo Med Pacman food as a portion of your pets’ diets. Continue to provide as much variety as possible, and choose from nutritious foods such as roaches, earthworms, sowbugs, minnows, crickets and silkworms. Please see the article linked below for other ideas, including the use of wild-caught insects.

 

In posts on other sites, some folks have expressed concern over the plant-based ingredients in this product, or the fact that fish is used as a protein source. While on-point research is lacking, it is well-known that frogs and other carnivorous animals take in a good deal of plant matter in the course of feeding upon herbivorous prey species. Fish, which I and others have long fed to many large frogs, does not seem to present any problems. Zoo Med Pacman Food also contains added vitamins and minerals, including calcium and Vitamin D.

 

Those who have tried will not need this warning (I’m sure!), but I should remind you not to feed Horned or African Bullfrogs with your fingers. The bony, tooth-like spikes that protrude from their jaws can inflict severe injuries. As most frogs seem to lack “self-control” when it comes to lunging at prey, use plastic feeding tongs only…sharp-edged metal models may injure your pets’ mouths.

 

 

 

Further Reading

Video: Using Pacman Food

African Bullfrog Consumes 17 Baby Cobras

Nutritious Live Foods for Frogs

 

 

Be it the discovery of a new species in the middle of NYC or the revelation that Mimic Poison Frogs are monogamous, frog enthusiasts are accustomed to surprises.  But those revealed in the last few years have been especially interesting and unexpected…frogs with sheathed claws, tadpoles that feed upon their father’s skin and on tree bark, bird-eating, bird-voiced and lungless frogs, fanged tadpoles and much, much more.  Were I new to this field, I’d consider much of the following article as pure fantasy…but even after a lifetime of working with amphibians, I’m still shaking my head.

 

Note: please see the linked articles for further information on the frogs introduced here.

 

 

Read More »

Hello, Frank Indiviglio here.  Although they are among the heaviest of the world’s frogs, African Bullfrogs, Pyxicephalus adspersus, do well in modestly-sized terrariums.  And by “doing well” I mean that they regularly live into their 20’s and 30’s…one even reached 51 years of age!  These amazing creatures stretch the limit of what most people think of as “a frog” – armed with tooth-like jaw spikes, males will defend their tadpoles from lions and dig trenches to deliver water.  Toughened by a harsh natural environment, African Bullfrogs are resilient beyond belief – one was observed downing 17 hatchling spitting cobras, and during droughts they can remain dormant for 10 to 12 months!  Please see articles linked below for more on their astonishing natural behaviors.

The following care guidelines can also be applied to the Dwarf African Bullfrog, P. edulis.

Natural History

African Bullfrogs inhabit seasonally-flooded savannas and swamps in much of Sub-Saharan Africa (please see habitat photo below).  They have been recorded in Swaziland, Angola, Botswana, Namibia, South Africa, Zambia and Zimbabwe.

In some populations, cannibalism supplies much food for newly-metamorphosed individuals.  I still recall BBC footage of adults taking down huge scorpions and centipedes while being bitten and stung numerous times.  I’ve been chased by Kodiak bears and crocodiles, but those scenes made me wince!  Invertebrates are their most common prey, but lizards, snakes, rodents and birds are sometimes taken.

The Terrarium

African Bullfrogs are relatively inactive.  A 15-20 gallon tank will accommodate an average adult, but a 30-55 gallon tank will be “appreciated”.

Important Note: Terrarium Hygiene

African Bullfrog terrariums must be kept scrupulously clean; ammonia poisoning (ammonia is released when the frog passes waste) is the most common cause of pet death.  Animals that have lived in perfect health for decades can be killed overnight if forced to remain in fouled water.  Please see this article.

Ease of maintenance is the main consideration when setting up the habitat.  Fortunately, African Bullfrogs get along well in simple accommodations.  A bare-bottomed aquarium, tilted on one side to create a small water section, is one easily-cleaned option.

Although they will happily dig into the substrate, African Bullfrogs are unusual among frogs in that they are quite content without a completely-secure hiding spot.  I favor plastic plants equipped with suction cups as retreats.  Simply attach the plant to the glass so that the foliage stretches nearly to ground level.  Your frog will push under the plant for shelter.  This has worked well for me in zoo exhibits and at home.

Substrate

African Bullfrogs are notorious “substrate-swallowers”, and are prone to intestinal blockages from gravel and other substrates.  Bare-bottomed terrariums or washable cage liners are safe options.

Former coworkers of mine began using coconut husk in a zoo exhibit awhile back and report that all is well.  The husk seems to pass easily though the digestive tract.  Several experienced private frog owners have reported the same.  I’m most interested in hearing of others’ experiences…please post below.

Light, Heat and Humidity

African Bullfrogs do not require UVB light, but may benefit from the provision of UVA.

Temperatures should range from 72 F on the cooler side of the terrarium to 85 F; a drop to 68 F at night may be beneficial.   Incandescent bulbs http://bitly.com/KbmGmC, night bulbs, or ceramic heaters http://bitly.com/KbmYKf can be used to warm the terrarium.

Although humidity is generally not a concern if they have access to a water bowl, overly-dry substrates may cause these frogs to burrow in and attempt aestivation.

Companions

Juveniles have insatiable appetites and invariably try to swallow even like-sized tank-mates.  Same-sized adults may co-exist, but should be fed separately as bites can occur at feeding time.

Feeding

African Bullfrogs, especially while growing, require a great deal of calcium.  Whole fishes and, to a lesser extent, pink mice, are ideal calcium sources.

Crickets alone, even if powdered with supplements, are not an adequate diet.  Minnows, shiners, earthworms, roaches and crickets can make up the bulk of their diet. Goldfishes may be used on occasion, but should not be a staple.

Pink mice may be offered once each 7-10 days, but are not necessary if fish are consumed regularly.  While some success has been had by feeding adult mice to African Bullfrogs, over-use of rodents may lead to liver problems and fur impactions (please see the article linked below).  While they certainly take the occasional rodent in the wild, invertebrates and other frogs make up the bulk of the wild diet.

Crayfishes (another good calcium source), butterworms, silkworms and other commercially-available invertebrates should also be included regularly.  Feeders should themselves be provided a nutritious diet; please see these articles on cricket and earthworm care).

Canned grasshoppers, snails, and silkworms offer an easy means of increasing dietary variety. Never offer food with your fingers!  Use plastic feeding tongs – frogs are “unable to control themselves” when hungry, and often suffer wounds when metal tongs are employed.

I feed cicadas, grasshoppers and other wild-caught invertebrates whenever possible. Please see this article for details and post any questions below.

Food (other than pinkies and fish) should be powdered with Zoo Med ReptiCalcium plus D3 or a similar product.  Vitamin/mineral supplements such as ReptiVite should be used 2-3 times weekly.

If you use moss or other substrates, meals are best offered via tongs or in a separate, bare-bottomed enclosure.

Water

Water should be changed daily and treated with a chlorine/chloramine remover.

Handling

African Bullfrogs have powerful jaws, the lower of which bears 3 (2 large, 1 smaller) sharp spikes known as odontoid structures.  They are actually bits of bone that extend up from the jaw, and can inflict serious wounds.  Fingers moved within reach will elicit a feeding response, and you will be bitten.

Fortunately, it is a simple matter to safely pick up an African Bullfrog by grasping it behind the front legs.  Amphibians should be handled only when necessary, and then with wet hands, so that you do not remove their protective mucus.  Wash well after handling any animal.

Please check out my posts on Twitter and Facebook.   Each day, I highlight breaking research, conservation news and interesting stories concerning just about every type of animal imaginable.  I look forward to hearing about your interests and experiences as well, and will use them in articles when possible.

Please also post your questions and comments below…I’ll be sure to respond quickly. 

Thanks, until next time,

Frank Indiviglio

 

Further Reading

African Bullfrog Eats 17 Young Cobras

African Bullfrogs: parental care of tadpoles

Feeding African Bullfrogs and Horned Frogs: Mice

Dwarf African Clawed Frogs, also known as Dwarf African Frogs (Hymenochirus boettgeri and H. curtipes) are very popular pets, yet few hobbyists attempt to breed them in captivity. Reproduction sometimes occurs spontaneously, but unless one is prepared, the eggs and tadpoles rarely survive.  As both a lifelong frog enthusiast and career herpetologist, I find this to be a sad state of affairs.  For these tiny aquatic frogs can be easily induced to breed and exhibit some of the amphibian world’s most amazing reproductive behaviors – including a circular egg-laying “dance” that may go on for 7 hours!  The bizarre tadpoles are equipped with tubular mouths and swim in a head up position at the water’s surface, propelled by rapidly-beating tails.  Looking somewhat like tiny skin-divers, rearing a tankful of these charming little amphibians is a most interesting and pleasurable undertaking.

Distinguishing the Species and the Sexes

Hymenochirus boettgeri and H. curtipes are the only species regularly available in the pet trade.  Hymenochirus boettgeri has proportionally longer rear legs than H. curtipes, and its skin appears more granular.  The tadpoles are easy to distinguish (please see below).

Females are larger than males, and they are positively rotund when carrying eggs.  Males can be distinguished by their postaxillary glands, which appear as a tiny white bump behind each forearm. Read More »