Home | Amphibians | African Clawed Frog, Xenopus laevis, Behavior – has anyone else observed this?

African Clawed Frog, Xenopus laevis, Behavior – has anyone else observed this?

African Clawed Frog

The opportunity to observe and record new behaviors is one of the most exciting aspects of amphibian and reptile keeping. Over the years, I have filled many notebooks with questions and observations. I would like to share them with you from time to time, and ask for your comments or notes about similar events you may have witnessed. Today I will ask for your thoughts on two incidents that have long puzzled me.

As you may know, the African clawed frog is entirely aquatic but may travel overland in search of water, but only when forced to do so – when its habitat dries out or poison is introduced to its pond. Many years ago I kept an adult pair that would lie out on a rock which protruded above the water, directly under an incandescent bulb. This only occurred in winter, when the water temperature in their tank averaged 66 F, so I thought they might be seeking warmth. However, others I’ve kept at that temperature have not left the water, despite being provided with a basking light as well.

The second observation involves a female clawed frog that laid eggs in absence of a male. That in itself is unusual, as most frogs utilize amplexus (the male grasps the female just behind the front legs or, in Xenopus, just above the rear legs) to induce egg laying. Odder still, however, was the fact that a male placed in the tank with the eggs (and without the female) on the following day fertilized the eggs. He was in breeding condition, as evidenced by the rough “nuptial pads” along his forearms, and perhaps was responding to pheromones or scents in the water, but still should have (according to me, not him, it seems!) required a female to stimulate sperm release. I have spoken with a number of herpetologists about this, and none can recall a similar incident.


Further information on this frog’s mating behavior and ability to travel overland is available at:

I also posted an article on African clawed frogs on That Fish Blog. If you’re interested in these guys, be sure to take a look at it too.


  1. avatar

    I remember reading a paper about egg parasitism in European Common Frogs (Rana temporaria), and it introduced the idea to me that certain amphibians may not only fertilize during amplexus… this is a common theory with Poison Dart Frog keepers (keeping the eggs with the parents for at least 48 hours because the male may repeatidly fertilize eggs) and it’s also an idea that egg guarding behavior is not just about predators… but males keeping other males from fertilizing eggs as well. Many (female) animals with internal fertilization mate with many different males to give the best chance for having mating success, so it figures the external breeders would have a way of doing it too…

    I recall an odd case of a weird frog morphing from a clutch of what seemed like normal Dendrobates azureus eggs… but one animal showed characteristics of being a hybrid between D. azureus, and D. leucomelas (also in the tank). Both species were proven with mates before being put together in the tank (thought to keep hybridizing from happening since they would have more prefered mates to court), and with the other clutchmates apearing to be perfectly normal Azureus, what happened? I believe it’s likely the male leucomelas saw eggs it thought would be it’s own species, and tried to sneak in his own genes.

    I think this behavior is more prevelant than we think…

  2. avatar
    Frank Indiviglio

    Hello Corey,

    Thanks so much for your interesting note and for the information concerniong the European common frog. The dart frogs are unique in not utilizing amplexus – I agree with you that male egg guarding functions to prevent other males from fertilizing the clutch.

    The differing courship rituals of the various species likely serve to prevent hybridization but once the eggs have been laid, certainly a male of another species could sneak in as you suggest. In fact, hybridization is common in mixed species dart frog exhibits at zoos, despite the fact that we do not see courtship between frogs of different species. Interestingly, the European common frog to which you referred also commonly hybridizes with near relatives.

    What surprised me about the African clawed frog incident was that this species utilizes amplexus before egg laying as its normal reproductive mode. This species and related species are considered to be “primitive” frogs and even use a different form of amplexus (inguinal, in which the female is grasped above the rear legs) than do more “advanced” species (such as the European common frog). Males even develop rough “nuptual pads” along the inner front legs to assist in grasping the female, and the bond thus formed is quite strong.

    African clawed frogs are perhaps the world’s best-studied amphibian (along with axolotls) and have been bred for countless generations in captivity – so I thought it would be a simple matter to find other examples of the behavior I noted. But neither several curators of major reptile collections nor the manager of the country’s largest frog breeding facility could recall a similar incident (in fact, most doubted me I’m sure!). Of course, given the clawed frog’s amazing ability to adapt to new, harsh environments, if any frog was going to take advantage of an opportunity to try a new breeding strategy, this would be the one!

    Many frogs that utilize amplexus do have to watch for competing males. Male American toads, Bufo (Anaxyrus) americanus, will try to dislodge others (and will kick at your hand if you disturb a pair in amplexus). Small male American bullfrogs, Rana (Lithobates) catesbeiana station themselves just outside the territories of large males. Unable to out-compete the larger animals by “wrestling” or by the tone of their voice, they intercept females swimming in to mate with the larger males!

    Thanks again – I look forward to your next observationn.

    Best regards,

  3. avatar

    Hey frank, i was cleaning out my ACF frog tank today with an algae scraper and saw a frog produce a very large substance from it’s rear. It was way too large to be excrement. I threw it away but I can tell you that the disgusting object was grey and slimy, it looked like a grey intestine with a small vein. Please do you have any idea what is it and is my frog ok?

    • avatar

      Hello Hamish, Frank Indiviglio here.

      Thanks for your interest in our blog.

      Clawed frogs sometimes swallow things that they cannot digest, i.e. plant leaves, gravel, and these are sometimes held for awhile, coated with a mucus-like material, and excreted…can also happen with a diet high in crickets (exoskeletons are not well-digested). May also be eggs which began to develop but did not go full term, scar tissue from an old internal injury, but hard to ID. Check also that your water is warm enough for proper digestion and that you’re not giving overly-large meals. Please write back with some details if you’d like to look into it a bit more.

      Good luck and please keep me posted.

      Best regards, Frank Indiviglio.

  4. avatar

    I am breeding clawed frogs and I have had multiple instances of one of my breeder females laying eggs on her own. This started way back when I got her as a froglet and continues today even in my all-female tank (I call it the brothel). I may try someday putting one of my breeder males in the tank when the eggs are laid, removing everyone but the male until he fertilizes them. My speculation is that the frogs are just being opportunistic- a male senses the eggs are unfertilized and does his part to spread his seed.

    • avatar

      Hello Kyle, Frank Indiviglio here.

      Thanks so much for your observation, I was beginning to doubt my memory and notes. I agree re opportunism – they certainly are the ultimate survivors, established in brackish tidal ponds, cold water supply systems in an old castle in England….

      Please let me know what happens if you do put a male in with eggs, yours would be the only such experiment I know of, other than the one I reported.

      If you have a chance, please let me know your tadpole diet…I used nettle tea extract many years ago, with mixed results.

      Thanks again, Good luck and please keep me posted.

      Best regards, Frank Indiviglio.

  5. avatar

    Hey, Frank- After experimenting with different foods, the one I am having the best results with is a mixture of freeze-dried bloodworms, Hikari turtle sticks, shrimp pellets, and Hikari baby bites, literally hammered into a fine powder. I find that even larger, denser pieces of food can be scooped up and filtered by the tadpoles. I have had no deaths with this food regimen.

    • avatar

      Hello Kyle,

      Thanks very much for the feedback. If you don’t mind, I’ll include your observations in a short article, I’ll let you know when it posts.

      The nettle tea seemed lacking in nutrients, although European hobbyists swore by it many years ago – source of tea may matter. The tads transformed, but all the metamorphs died after a few weeks (in different collections). Your diet makes great sense.

      I was a teenager at the time, and the tea was sold in “rough form” – a bag of chopped up leaves and stems. I bought a bag each week – later found out that the clerk at the small health food store suspected I was using it as part of a drug-selling scam – not many folks feeing it to tadpoles at the time!

      Good luck and please keep me posted.

      Best regards, Frank Indiviglio.

  6. avatar

    Hey Frank,

    While I don’t have much to offer in terms of ACF’s basking (I have never even considered offering them a basking rock considering their fully-aquatic nature. I might have to offer mine one now out of curiosity), I have witnessed a female laying eggs without a male present.

    I had kept ACFs when I was a young boy, but had donated mine to my school when I was 12 or so. About a year ago I decided to get back into keeping the voracious little monsters so I picked one up from my local pet store here in Cincinnati.

    After having her for a couple of months, I had to go out of town for a few days on business. Unfortunately for my frog, it was mid-December and I had forgotten to leave my heat on. When I returned home the water temperature in the frog tank was in the low 50’s and the ACF was completely immobile. I reached in to check for life and surprisingly she did move away from my hand, albeit very lethargically.

    I quickly turned the heat up in my house and made a trip to the pet store to pickup an aquarium heater. While there I also grabbed a wonderfully twisted piece of mopani driftwood as a hide (she had outgrown her previous hide) and some ReptoTreat bloodworms as a “peace-offering” of sorts for almost freezing the poor little thing to death.

    I waited a day or two for the temperature to rise in the tank just from the ambient air in my house before adding the heater as I didn’t want to shock the little thing with another drastic temperature shift. After adding the heater and mopani wood, I feed her a packet or two of the ReptoTreat bloodworms, which she eagerly gobbled up, along with a few floating sticks and freeze-dried krill.

    The next morning I noticed the mopani wood, even after what I thought was a thorough boil and soak, had released so much tannin into the water that it looked like a ten gallon pot of tea. Much to my surprise, I also noticed that the mopani wood was now dotted with dozens of little eggs.

    I was very confused by this as the last time she was in contact with a male was several months prior when she was at the pet store. All I can figure is that somehow the combination of the sudden change in temp (She was usually in the mid 60’s to low 70’s before the quick dip into the 50’s, and 75-78 after the addition of the heater), the extra tannin in the water, and the belly full of bloodworms triggered her to spawn.

    It has been about 5 months now since this incident and she hasn’t laid eggs since, although she has probably doubled in size. I wish now that I had had access to an adult male to see if he would have fertilized the eggs as you described.

    Sort of amazing that there is anything left to discover about the behavior of these entertaining little frogs, considering their long history of captive breeding and scientific study.


    • avatar

      Frank Indiviglio here.

      Thanks for taking the time to write in with your observation…I’ll keep your notes on file for future reference – several herpetologist co-workers still doubt me!

      A dip and rise in temperature can stimulate egg-production; in the wild they tend to lay during rainy periods following a drought; in introduced habitats that are temperate, rising temperatures are an important breeding stimulus. As you surmise, the tannins may have played a part – pH changes often accompany changes in water level or the addition of rain water in nature. I’m glad that you included the temperatures/timing of the event; very useful.

      Yes, as you say – these guys are full of surprises even after all this time; some new meds being teased out of skin secretions, introduced populations found in brackish ponds, underground water systems of castles in England – no end, it seems. Please keep me posted on your future experiments/observations – I’ve been keeping these and related species since boyhood, yet never tire of them.

      Good luck and please keep me posted.

      Best regards, Frank Indiviglio.

  7. avatar

    you wanted imput on some odd behaviors of clawed frogs i have 4..they share residence with a couple tinfoil barbs which are much too large for the frogs to eat…..my tank faces toward my couch in my living room, and we see our largest frog frequently standing on a rock or log looking at us like he wants a “hug” i dont know if its a ambush thing or not…but serveral times a week i hear my kids saying hey dad the frog wants another hug lol

    • avatar

      Hello Ray, Frank Indiviglio here.

      Thanks for the very interesting observation. Stebbins (Peterson Guide to Western Reptiles and Amphibians) gives the upper elevation limit as 4,500 feet; there is one “sight record” at 6,790 feet, so your observation is significant. CA Fish and Game or another relevant state body might be interested in hearing from you (I’ve not checked recent field research reports – these are scattered in journals and take time to reference). I’m going to forward your note to a special interest (constrictor) group.

      Rosy boas are found in an amazing array of habitats – I’ve observed them in the deserts of Baja California, and they have been found in Death Valley, below sea level.

      Thanks again and please keep me posted.

      Best regards, Frank Indiviglio.

    • avatar

      Hello James, Frank Indiviglio here.

      Thanks for the interesting note. It’s not well known, but they are, as you suggest, ambush predators – they seem to specialize in leaping at low flying insects from a floating position. The typical submerged posture – fingers and arms spread – also allows them to grab at anything that swims near or brushes against the nerve-infused fingers. In outdoor ponds, I’ve even observed them to come ½ way out of the water to grab insects near the pond’s edge. Hugging is tough, though – they tend to shoot out of one’s arms and across the room!

      Good luck, enjoy and please keep me posted.

      Best regards, Frank Indiviglio.

  8. avatar

    Hello Frank, there hasn’t been a post on here in quite some time, but I’d still like to write down a couple things about my ACF, it tends to do similar stances as James S’s where it appears to be standing up, just barley against the glass. I have it as a tank-mate with a few decent size koi and goldfish that I take in for the winter, their big enough to not get eaten but it sure does try! Sometimes it will almost smush itself between the back of the tank and the over the back filter, possibly so it can get a different viewing angle, I have seen it use that method at just barley the surface so it can breath for a while without moving with the current.

    I have not tried giving it a surface to which it can actually get out of the water, but it did escape to the carpet floor once! it was when i first acquired my ACF from the local pet-shop. At that point it was still small enough that i thought my decent size goldfish may have eaten it while i was at work. But then randomly i see something moving on the floor as I am watching tv! I thought OH NO not another mouse!! It was my little ACF! I was so supuriesed i took it and rinsed off the carpet fibers and quickly acclimated it to the tank again!

    I have had a ACF in my tank with the friendly baby koi and the koi/ one big goldfish i take in for the winter.

    I have lots of time invested on watching this frogs behaviors, as well as the behaviors of the fish. I wish i had started a journal earlier about the habits and what kind of things i see. I have started now thanks to you webpage!

    I also have not tried getting another, mainly because every time i see them at the local pet-shop they are the Dwarf Variety.

    In good hopes you’ll reply,

    Christopher P.

    • avatar

      Hello Christopher, Frank Indiviglio here.

      Nice to hear from you again. Thanks for the observations and kind words; Af Clawed frogs seem to take up those positions in order to grab insects that fall onto the water…apparently a big part of their diet in the wild. Some species that occasionally appear in the trade (X. tropicalis and X. meulleri) actively leap above the surface to catch flying bugs; the typical pet store species, X. laevis, may also do this.

      Dwarf clawed frogs Hymenochirus sp are interesting but need live food and cannot be kept with larger species or fish.

      Very glad to hear you are keeping a journal…useful, fun and a lost art today. I still refer to notes that I first made decades ago!

      Please let me know if you need any further information. Good luck, enjoy and please keep me posted.

  9. avatar

    I have been the proud owner of a female African clawed frog for 3 years, and I’ve noted many interesting behaviors. She’s very responsive to me, when I first bought her (she was barely a ½ inch!) she would often swim to the corner of the tank closest to me. She will also nibble at my fingers, or even bite them, and will almost always take food from my fingers. I have placed many artificial plants around her tank as “hides” and she will on occasionally rearrange them. She is particularly fond of toppling over one in particular, and standing it up again! Something else unusual is how she will rise to the surface when I’m cooking something fragrant, such as meat, she will rise to the surface and float at the top with her nostrils flared. She and I also have a “game” that we “play” where if I wiggle my finger, she will follow it. I usually follow this up with some sort of food treat. I have been trying to create a photo journal of this behavior, but she has proven to be very camera shy. I don’t blame her, I have a giant black Nikon, which would probably scare the crap out of me if I was a little frog, but I’m slowly seeing if I can’t “teach” her that it’s not going to harm her. I’m not sure if frogs can be trained like dogs and cats, but I’m willing to give it a try.
    During my time with her, I’ve noticed the egg-laying without a male. I’ve also heard her making clicking noises up to a week prior to the egg-laying. I thought it was triggered when I changed her water at first, having been uneducated on proper ACF care at the time, I would give her warmer water. I later learned (after correcting this mistake!) that the egg-laying was not triggered by that; she’d be clicking and laying eggs just the same. She’d ovulate about once a month for a while. My current theory is that it is triggered by her consumption of houseflies. I often swat and feed them to her, because she seems to enjoy them, but she’s been proving me wrong yet again since I’ve removed them from her diet and she’s been clicking steadily every night this week. I’ll have to experiment some more.
    I’ve read in articles that ACF’s have been used as pregnancy tests. From my experience in biology classes, the hormone that causes the frogs to ovulate that is produced by pregnant women, and is present in the urine, is called human chorionic gonadotropin, or hCG. I am not sure if it’s something in the water that may be imitating this hormone in frogs, or maybe their adaptation to survive. I’d be very interested to find out.

    • avatar


      very interesting observations, thank you. They are able to make associations and learn new behaviors, and to become accustomed to things such as the camera over time; food/fear, as you’ve seen, are the main influences in this.

      ACF and other amphibs do respond to chemicals in the water, including pesticides…males have developed ovaries in lab tests, etx. However, females in good health nearly always have partially developed eggs in waiting..unlike most others, they can reproduce year round, whenever conditions are favorable. Laying without amplexus, however, seems not to be common. Please see this article.

      keep an eye on water quality as she grows…ammonia levels can rise unnoticed; be sure to increase frequency of partial water changes,add a stronger filter, etc.

      Enjoy, Frank

  10. avatar

    I have a question. In many care sheets filtration for these frogs is discouraged, because it is said that the vibrations stress them. Others though put filters without problems. What is the truth?

    • avatar

      Unless tank can easily be dumped/cleaned regularly, they should be filtered; strong currents that interfere with swimming should be avoided, but vibrations and such are not a concern; I have several in their 20’s in filtered tanks, related species as old in zoo exhibits. They are very sensitive to ammonia, o partial water changes are impt even with filtration. Best, frank

  11. avatar

    Thank you very much for the clarification.

  12. avatar

    My frog just laid eggs all by herself -At least now I know it’s a female. I actually always thought it was a male since the hands were a little dark. Will be seeking a male at the pet shop for assistance with fertilization.

    • avatar

      Hello Kenny,

      I’m very interested to hear what happens…please keep me posted. he may have more eggs, so you might want to try putting male in with her; if you have space, perhaps put him in with eggs alone (absent female), so you’ll be able to learn if he fertilizes those eggs as well. Enjoy (or, hope he and she enjoys!) Frank

About Frank Indiviglio

Read other posts by

Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.
Scroll To Top