Home | General Reptile & Amphibian Articles | Alternative Substrates: Oyster Shell for Desert-Adapted Lizards and Tortoises – Part 1

Alternative Substrates: Oyster Shell for Desert-Adapted Lizards and Tortoises – Part 1

Reptile and amphibian keepers are fortunate to have at our disposal a huge array of substrates, many of which are formulated for specific animals (burrowing frogs, large snakes).  However, there are still a few situations, usually involving especially sensitive species, where we may need to improvise.  Today I’d like to relate my experiences using “alternative” substrates for desert-dwelling reptiles and hatchling tortoises.  I have long used both while working with animals in zoos, but have noticed that neither is well-known in the pet trade.

The Immune Systems of Desert Dwellers  

Reptiles hailing from desert and semi-desert habitats are often very sensitive to molds and fungi.  Having evolved in unique, relatively pathogen-free environments, their immune systems are usually unable to adapt to attack by microorganisms commonly encountered in captivity.

Potential Problems with Sand

Many of the substrates traditionally used for such creatures, including most types of sand, harbor molds and fungi when damp.  Although not a problem (in limited-contact situations) for all desert animals, some are especially sensitive and quickly succumb to skin and respiratory infections.

Chief among these in my experience are Egyptian tortoises (Testudo kleimanni), padloper tortoises (Homopus signatus, the world’s smallest tortoise) and several of the whip-tailed lizards (Cnemidophorus spp.).

Using Oyster Shell

Oyster shell (available at garden and poultry supply stores) does not support the growth of fungi or mold, is benign when swallowed in small amounts, and can be easily spot-cleaned and discarded when fouled.  I cannot recall any skin or respiratory problems in desert-dwelling reptiles maintained on oyster shell.


Further Reading

You can read more about fungal and other respiratory ailments in tortoises at: http://www.azeah.com/Care-Sheets.asp?id=125

Tortoise photo referenced from Wikipedia and originally posted by Stefano Alcini.


  1. avatar

    Hello! I have a hatchling Egyptian, and I originally started out with oyster she’ll until I realized I was allergic to it.

    What other type of substrate could I use for my tortoise, aside from rabbit pellets?

    • avatar


      You can keep them on a mix of dry top soil and sand; feed from a bowl and place the bowl on newspapers to prevent substrate ingestion. I’ve not run across references to allergies…you may wish to check that symptoms are not related to another health problem (respiratory infection, etc). Best, Frank

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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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