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Contains articles and advice on a wide variety of amphibian species, including frogs, toads, salamanders and caecilians. Answers and addresses questions on species husbandry, captive status, breeding, news and conservation issues concerning amphibians.

Keeping Captive Amphibians Healthy – bacteria, fungi, parasites and other considerations – Part 1

The prevention and treatment of disease in captive reptiles and amphibians has advanced greatly in recent years. Unfortunately, however, there is still a great deal that baffles us — our knowledge of amphibian medicine in particular is quite poor. On the positive side, we do know a quite a bit about the diagnosis and treatment of disease in tropical fishes, and much of the basic research behind this is applicable to amphibians.

General Notes Concerning Amphibian Health Care
Among the most important steps you can take to insure the health of your pet amphibians is to establish a relationship with a qualified veterinarian. Veterinary practices specializing in amphibian medicine, although by no means common, are on the increase. Your local herpetological society should be able to provide some leads.

Many medications designed for use with aquarium fish work well on related conditions in amphibians. Bare in mind, however, that amphibians absorb medication over a much greater area surface area that do fish — in many cases, the entire skin of the amphibian will allow transfer of the medicine. Although I have had success using certain medications in the same dosages as are recommended for fish, I always begin treatment with a 50% dilution and watch carefully for signs of stress (gasping, swimming about wildly, scratching, skin sloughing).

Good hygiene is the basic starting point for avoiding sickness, and, in some cases, even for treatment. Again, the porous nature of amphibian skin is a consideration – ammonia from waste products and other toxins in the terrarium will be absorbed through the skin if not removed.

Bottled spring water (not distilled water) should always be on hand. Salamanders and frogs suffering from ammonia or other chemical toxicity can sometimes be revived by placing them in such water and allowing it to flush harmful chemicals from the body.

Considering how little we know concerning the treatment of disease, prevention is vital. Always be sure to keep your pets in a secure, stress-free environment and provide each species with the appropriate temperature, humidity, light cycle and diet.

Amphibian skin is extremely delicate, and its mucous covering repels attacks by harmful microorganisms. Extreme care must be taken in administering injections and in handling frogs and salamanders. Amphibians should be held with wet hands only, or confined within a water-filled plastic bag when being examined. Catching a frog or salamander with a stiff nylon net may also remove some of the skin’s mucous coating and expose the animal to bacterial infection. When in doubt, use a preparation designed to replace the mucus coating of aquarium fish.

Due to the nature of reptile and amphibian circulatory systems, injections of most medications are given in the front legs. If multiple injections are needed, a different leg, and a different site on each leg, should be used. This will go a long way in avoiding damage to the delicate skin.

The details of all the medical treatments administered to your pets should be recorded. Not only will this prevent mistakes, especially when you’re experimenting with different dosage levels, but a record of what you have done will also be very useful to yourself and others in the future, and may even lead to a new discovery. Trust me on this – write it down, you will not remember in years to come!


Chemicals (pesticides, Atrazine, gonadotrophin) and Their Effects on Frog and Fish Sexuality and Reproduction

download (2)Amphibians and fish are highly susceptible to even minute amounts of foreign chemicals in their habitats. As such, their current population declines should serve as an important “early warning signal”, forecasting problems that will eventually affect other animals and ourselves.

An odd twist to this sensitivity issue among frogs is that an injection of gonadotrophin, a human growth hormone, brings many species into breeding condition. This discovery was a boon to captive breeding programs, as most frogs require the duplication of certain environmental cues – dry or wet seasons, for example – if they are to breed normally. However, things can easily go wrong – while using hormones to stimulate breeding, I and others have noted that some male frogs began to develop organs resembling ovaries.

Now, male frogs in the wild are being found to have inter-sex characteristics, including immature eggs within the testes. A recent Harvard University study found such characteristics in 21% of the male green frogs, Rana clamitans, in ponds in suburban Connecticut. It seemed that the affected frogs were more common in suburban than agricultural areas, but other studies have yielded opposite results. Similar reproductive system changes have been documented among catfish in Africa, sturgeon in the Mississippi and other fishes.

Drainage_nitrates_vers_HondeghemFr_2003_04_09Pesticides, the herbicide Atrazine, and other chemicals commonly found in water and soil have been shown to affect sex hormone development, but much more research needs to be done.

There is a great deal of ongoing research in this important area – please read any related articles that you may come across and write in to share new information.

An article describing research into the effects of Atrazine on amphibians is posted at:http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1247376

Algae and Salamander Eggs – an odd partnership

Spring Peeper
Spring in the northeastern USA is prime time for amphibian watchers. Its arrival is most noticeably announced by frogs – first by spring peepers, Pseudacris crucifer and wood frogs, Rana (Lithobates) sylvaticus, with a succession of others following close behind. However, the season’s earliest greeters are silent. I have observed tiger salamanders Ambystoma tigrinum, move into breeding ponds during warm spells in late January (Long Island, NY).

Another amphibian that breeds in early spring is the strikingly marked spotted salamander, A. maculatum. Reaching 9 ¾ inches in length, these stout animals are jet black with yellow spots, and have been observed crossing snow during breeding migrations (I find them in ponds in southern NY in mid-March).

Amazingly, a species of green algae, Oophila amblystomatis, colonizes the spotteSpotted Salamanderd salamander’s globular egg masses. The algae most likely utilizes carbon dioxide and ammonia produced by the developing salamander embryos, and may in turn provide the embryos with oxygen (although the amount released is quite low). There is speculation that the algae may produce a growth factor that benefits the embryos, but more research is needed. In any event, experiments have shown that egg masses with this algae hatch faster, and with a higher survivorship, than do those lacking the algae. Conversely, algae growth slows markedly if the embryos are removed from the egg mass upon which it is established.

Spotted salamanders make interesting pets, and, while adapted to a burrowing lifestyle, adjust well to life above ground. Properly cared for, they can live for over 25 years. I will discuss them further in a future article.

More detailed information on this unique relationship is available at:

Amphibian Learning Abilities – the southern toad, Bufo (Anaxyrus) terrestris and bumblebee mimics

While thinking about amphibian learning capacities recently, I was reminded of an experiment recounted in the book Animal Behavior (Time, Inc., 1965), written by Niko Tinbergen, one of the giants in the study of ethology (animal behavior). The experiment was conducted at the famous Archbold Research Station in Florida, in the 1960’s.

The robber fly, which is sting-less and tasty, closely resembles the unpalatable bumblebee. A southern toad, which had previously seen neither fly nor bee, was presented with a robber fly, which was promptly eaten. A bumblebee was then offered – the toad grabbed it, was stung, and spit out the bee. A subsequent bumblebee was refused. Then another robber fly was offered – and, its lesson learned, the toad backed away. To prove that the toad was still hungry, the researchers then provided a dragonfly, which was immediately eaten.

I am not aware of research concerning how long such lessons are retained – but my own experience offers some clues. I have long kept green frogs, Rana (Lithobates) clamitans in an outdoor pen, where I used ripe fruit to attract insects for them to eat. Year after year, I observed the same frogs to studiously avoid yellow-jackets and other wasps, while snapping up flies and beetles located close to the wasps. It would appear that they were stung at one point, and that the lesson lasted, as far as I can tell, for at least 6 years.


The book to which I referred above is one in the wonderful Life Nature Library series published by Time, Inc. Don’t let the publication dates fool you – they are packed with original observations and unique photos.

An Appetite for Cobras: Huge Bullfrog Meals

Pixie Frog
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.
American Bullfrog
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:

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