Home | Amphibians | Choosing the Ideal Substrate for Reptiles, Amphibians and Invertebrates – Part 2

Choosing the Ideal Substrate for Reptiles, Amphibians and Invertebrates – Part 2

In Part I of this article we reviewed some general points to consider when choosing a substrate – moisture retention, suitability for burrowing and so forth.  Today I’ll examine specific types of substrates more closely.

A Note on Substrate Ingestion

We do not fully understand why captive animals sometimes suffer intestinal blockages after swallowing substrates that they likely consume in the wild without incident.  It may be related to the consistency of the foods they eat, hydration levels, health or even micro-nutrient intake (for example, Calcium is essential for proper muscle contraction…a deficiency may affect the passage of food through the digestive tract). 

Until we learn more, use caution, even with products claiming to be safe if ingested.  When unsure, use a feeding bowl or tongs to limit accidents.


Bark BeddingBark absorbs water to a certain degree, rendering it useful for Anoles, Ribbon Snakes and other reptiles that need moderate humidity, but is not as well-suited for amphibians (the edges may be a bit too rough for sensitive skins also).  It can also be used dry for arid-adapted species.

Products containing Eucalyptus and Cypress Bark help control odors and may also retard the growth of bacteria, mold and fungi.  I’ve long used these, and Hardwood, Aspen Barks, for zoo exhibits and large snakes, lizards and some tortoises.  Hardwood Bark is also suitable for small mammals and birds.


Many amphibians are at home in mossy surroundings.  Sphagnum Moss is one of the most ideal amphibian substrates of all, and can also be used with certain reptiles (i.e. Crocodile Skinks).  It has great water-retaining properties…with a bit of practice you can adjust the moisture level in it and the terrarium quite well.

Burrowing amphibians such as Tiger Salamanders and Smooth-Sided Toads, which would normally utilize soil in the wild, take to Sphagnum readily.  I often mix it into topsoil when keeping animals that burrow deeply, such as Giant Bird-Eating Spiders – burrows dug into this mixture retain their shape well.

Moss assortmentSphagnum is also indispensible for creating damp areas within shelters or egg-deposition sites.  By wedged it into tree hollows or rolled Cork Bark, you can also create moist hide-aways for Treefrogs, arboreal Tarantulas and other tree-dwelling animals that are usually reluctant to use ground-level caves.

Sphagnum is difficult to swallow, and I have not run across any instances of it having caused an internal blockage.  It may begin to grow under the right conditions – spores and seeds within it may sprout as well!

Compressed Frog Moss is an interesting product.  It expands when hydrated with water and is excellent as a “crevice-filler” or when mixed into other substrates to bolster water-retention.  Some folks use it as an egg-incubating medium as well.


Calcium sandSand finds use in desert terrariums and can also be mixed into soil and used for burrowers from semi-arid habitats, such as European Glass Lizards and Spadefoot Toads.

Fine grade, Calcium-Infused Sand should theoretically be harmless or even beneficial if swallowed, but please see the note at the beginning of this article.

Sands of gold, black, white, mauve, orange and other colors allow one to mimic specific habitats when setting up terrariums.



Further Reading

Please see my article Substrates for Animals Prone to Intestinal Blockages for more on this important topic.



  1. avatar

    What a timely article! I am currently placing a page on my site listing all the substrates with some pro’s and con’s. Though that does not serve to answer ….What should I use?…that is out there on the net everyday in the forums. I believe there is a range in which we can be successful keepers. My next quest, is to find the why, each of us choose the husbandry style we do. Here is one of the answers I have been given permission to reprint.

    Hi Pat, I just wanted to respond to questions posed in your thread. I might add that this is a welcome break from the usual banter on the forums…

    creative minds vs. stat/math/analysis minds?
    Cannot comment here, but for myself it’s a bit of both left and right brain. I’d like to be more creative in the overall setup, but I’m forced to be as practical as possible. Quite simply, I dont have the time or the room or the money to do what is pictured in my head

    why have you chosen the route to take in your home?
    We are a working household, we had to strike a compromise between what was efficient in terms of the work involved on an often tight schedule. That being said, we still wanted to provide a modicum of natural environment for our fella (a red foot tortoise)

    What was involved in your decision making process?

    – securable, appropriate location within residence
    – availability of space
    – materials available
    – ease of access (mom has arthritis and must be able to access the animal)
    – ease of cleaning
    – safety issues (small curious dogs)
    – providing a reasonable environment for the animal without going broke

    Similiar guidelines were followed when establishing an outdoor pen, with greater latitude for space requirments.

    Explain to me your reptile keeping philosophy?
    Based on what’s realistic and achievable, factoring in care requirments and budget. Obviously, we arent going to have an indoor tortoise pen covering several square yards, as ideal as it may be for the animal. We focus moreso on the animal’s dietary needs and it’s basic requirments (humidity, uvb, heat requirments). Having a really fancy-schmancy setup is going to be an exercise in futility when keeping torts, as they arent especially aware of aesthetics. Essentially, the animal trashes the enclosure on a daily basis. Because the tortoise tank is dirt bearing, I use springtails and isopods as soil cyclers, thereby extending the service life of the substrate greatly.

    What kind of commitment and organizational ability is needed to be successful within the style that you work in?

    Relatively easy IMO. Commitment amounts to about an hour a day minimum, excluding “play time”. A fairly loose and varied feeding schedule, but regimented bathing and water tub changes as tortoises can be somewhat filthy by our standards. One day on the weekend, I spend a couple hours cleaning the tank, being more meticulous than on a weekday. We also prepare food in advance for the animal, ingredients are selected with very high standards and mixed by us at home. In terms of organization, minimal time management is required. The tasks are reasonably simple and not especially strenuous, though often frustrating when the animal defecates in the enclosure. We’re “training” the animal to defecate in the bathtub, as the feces is more easily dealt with

    Untracked time spent with the animal includes as much free ranging as possible under the circumstances, and random interactions with the creature.

    Kind regards to you, Frank.


    • avatar

      Hello Pat, Frank Indiviglio here.

      Thanks for your interest and for passing along the comment.

      As mentioned there, I think it’s wise that folks consider all that may be involved in herp care – most often, unfortunately, they are taken by surprise.

      I would like to point out, re the comment about “training” the tortoise to defecate in a bathtub, that I counsel folks never to allow animals, food bowls etc. in bathtubs or sinks used for preparing food for people. The risk of transmitting a serious disease is just too great. A doctor should always be consulted concerning proper disinfection practices if animals are cleaned near areas used by owners.

      Good luck, enjoy and please keep me posted.

      Best regards, Frank Indiviglio.

  2. avatar

    I appreciate the guidance for others reading the submission.

    Thanks much. See you soon.


  3. avatar

    Hello Frank,

    Interesting topic and one of great debate constantly amongst people keeping captives.

    I had to put in a comment on potty training tortoises. A family friend of mine kept a redfoot tortoise which somehow or another he managed to potty train. In the morning, he would take the tortoise to the bathroom and hold it over the toilet and it would go about its business(if not, flushing the toilet would often prompt it!).

    • avatar

      Hello Joseph,

      Yes… it’s hard for me to understand why so many people still seem to be unclear on this topic. The guidelines established by the Ass. of Reptile/Amphibian Veterinarians are very useful.

      Thanks for the interesting story…tortoises almost always defecate quickly when places in water – a useful trick for keeping exhibits/cages clean. I imagine your friend’s animal made the association when carried to the toilet (tortoises are very good at that – please keep an eye out for my new article on learning abilities in tortoises).

      Good luck and please keep me posted.

      Best regards, Frank Indiviglio.

  4. avatar

    Excellent reference, will refer to that. People often reference Melissa Kaplan’s website too with much information as well as an article on herps and kids.

    I guess the main thing is whether or not herps pose a higher chance of zoonotic disease compared to more common pets…dogs, cats, birds etc.


    • avatar

      Hello Joseph,

      Just about any creature can harbor Salmonella, Giardia and others; Sliders became associated with Salmonella in the late 60’s as the crowded conditions in which they were raised guaranteed infection. Also, many herps seem to harbor 1 or more of the 1,500+ species of Salmonella as a normal part of the gut flora.

      Best regards, Frank Indiviglio.

  5. avatar

    Right now I have my juvenile Savannah on Zoo Meds’ aspen snake bedding, but I’m beginning to rethink that decision and considering getting reptile carpet instead. Even though I present his food in a bowl he just insists on dragging whatever it is out onto the bedding and then proceed to rub it all over. With dry food this isn’t a problem, but when I give him fish, canned insects or anything moist then the aspen sticks in clumps. So far there hasn’t been a problem, but I can’t help but be concerned. I apologise for all the comments by the way.

    Cheers, Alex

    • avatar

      Hi Alex,

      Please keep the posts coming..great points and very useful to other readers. I agree with you on the aspen bedding. It has been used w/o incident, but there are potential problems if too much is swallowed. Cage carpets simplify cleaning, generally allow for a better environment, health-wise. Easiest to have a few handy, so one can dry thoroughly (in sun, if at all possible) while replacement is being used. Clean with 1 oz bleach per gallon of water or a reptile-safe disinfectant.

  6. avatar

    I read a book called The Savannah Monitor Lizard: The truth about Varanus exanthematicus, and in the book it says that flat substrates like carpeting and paper towels are the worst because they can’t dig into it. While dirt and others where they can burrow into are best. It was written by a guy who studies them in the wild. It’s an ebook and I can email you a copy if you’d like to browse it.

    I guess it’s just a balance between keeping them safe and keeping them natural.

    Cheers, Alex

    • avatar

      Hi Alex,

      Thx for the feedback. That is a very good point. There are some animals that must be given the opportunity to burrow – deny a trapdoor spider or spadefoot toad substrate, and it will perish. same re climbing opportunities, etc. Savannas are quite adaptable in this regard,. however, and generally do fine; wild caught animals may be an exception, but even that would be rare. Breeding cages might be another area where you would opt for burrowing if possible. During my zoo years, I kept and bred many species on bare floors, rubber mats, etc. As you say, a balance – cages that allow for exploration, hunting, digging etc are more interesting, in general, but harder to maintain and mainly make a difference only where spacious facilities are provides. Certain monitors do need set-ups that more closely resemble their natural habitats (bad term – beyond impossible to do that, but it’s what we use…) – I’m thinking here of black and green tree monitors and other small, shy arboreal species.

      Best, Frank

About Frank Indiviglio

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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.
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