Bioactive is a fairly new concept in the world of keeping amphibians and reptiles. While commonly utilised for tropical species at first, the method is branching out into arid environment setups. Making a bioactive enclosure for desert reptiles is not as daunting as once thought, and can be a rewarding project for both you and your animal. Here we outline the essential components that go into a bioactive setup for a desert reptile.

Arid Bioactive Setups – A New Frontier?

A Moroccan Uromastyx basks in the sun.

The world of exotic animal keeping is always changing and expanding together with the growth of scientific information. When it comes to reptiles, there have been great strides within the last decade towards improving husbandry practices in pursuit of the best possible quality of life and longevity of our animals. A method of keeping reptiles (plus amphibians and invertebrates) that is ever increasing in popularity in the hobby is the bioactive setup. Tropical rainforest setups are already quite well known for bioactive applications, but this method is now expanding to arid environment species as well.

What do we mean by ‘bioactive’?

The ways people have kept their reptiles has been variable from the beginning, with many points of debate (to put it lightly). In more recent years, the majority of hobbyists are in agreement that the ‘sterile’ type setups using kitchen towels or linoleum as substrate with minimalistic decoration are lacking in the enrichment needed for animals to really thrive, rather than just survive.

For new animals in quarantine or animals that are sick, it is definitely a good idea, but not so much for the long term. The original fear was due to misconceptions spread about the risks of loose substrates – such as sand – and impaction of the gut. Most of us have heard horror stories of death or serious illness caused by impaction, but it is clear now that impaction is a result of wider husbandry being inadequate. It simply comes down to the fact that in the wild, desert reptiles like bearded dragons and leopard geckos are not safeguarded by paper towels. They live their whole lives exposed to natural substrates. If you want to simulate the most accurate environment possible for your animal compared to nature, loose substrates are going to be part of the deal – along with a handful of other components.

The aim of creating a bioactive setup is to simulate a contained, mini ecosystem mimicking that which is natural to your animal. This involves naturalistic substrates, plants, and invertebrates. Once established, these mini environments are self-maintaining, vastly reducing maintenance required by you, and adding enrichment for your animals.  Here we break down what you would need to create your very own arid bioactive environment suitable for leopard geckos, as an example. With some tweaks to species specifics, this can be done for pretty much any other type of reptile!

The enclosure

You’re going to want enough space for your animal, as well as room for all of the plants and décor and to accommodate the light sources. For leopard geckos, the minimum recommended enclosure size for one adult is 90cm x 45cm x 45cm, and you can certainly go bigger. Going too small can impair the regulation of different zones of temperature and humidity.

For wooden vivariums, sealing the edges with animal-friendly sealant is recommended to prevent any moisture leakage which could damage the materials over time or allow small bugs to escape. Some go so far as to use a waterproof coating on the wood as well, to protect it from long-term damage from any humidity. It’s less of a problem with arid setups, but something to consider investing in. A natural background can really complement a bioactive enclosure, so consider if you want to use one before adding everything else!

Lighting and electronics

It’s probably easiest at this point to get your lighting and heating installed. There is some debate between under-tank heat mats and ceramic emitters for leopard geckos. Either way, you need to ensure correct temperature maintenance and heat penetration. Because bioactive substrates require deep layers, UTH mats can struggle to provide enough heat, and risk overheating. Stuck to the side of a glass terrarium instead of the bottom, they can work. Ceramic lamps spread heat downwards from above, avoiding the substrate issue. To control the environmental temperature properly, you must use a thermostat. Dimming or pulse are better for temperature regulation as they can maintain more accurate temperatures (by providing continuous heat) than on/off thermostats. Hygrometers and thermometers are necessary to monitor the temperature and humidity in your bioactive setup.

It’s no secret that reptiles benefit from UVB lighting, and leopard geckos are no exception. In simulating the most natural environment for them it’s a given to provide your reptile their natural daily UV light exposure. Being crepuscular with only sporadic times under the sun, leopard geckos don’t need a high intensity. A UV Index in Ferguson Zone 1 is plenty for a ‘shade dwelling’ species – you may know this as ‘2%’ UV or similar. Be sure to research your specific animal’s UV requirement and find the best light fitting for them, according to their enclosure dimensions.

Lastly, if you’re using live plants in your setup, they will need specific lighting to facilitate their growth and health – UV lamps alone will not provide enough photosynthetically active radiation (400 to 700nm) that allows plants to thrive. This value will vary between plant species, so it’s best to check what your chosen plants require and that the lighting will provide this. If you’re unsure, different lights will specify their emitted wavelengths and use for plant growing. There are a range of LED lights on the market that are appropriate for live plants.

This is a visual guide by Reptile Systems to the Ferguson Zones – UVI requirements for reptiles depending on their natural environments and behaviours. See that leopard geckos are classed in Zone 1, while other desert species such as bearded dragons reside in Zone 3-4.

Substrate

Now for the bedrock of the setup – the substrate. Although arid environments like leopard geckoes and beardies bring ‘desert’ to mind, these environments do not consist of pure dry sand dunes – in fact very few deserts are made up purely of sand. The habitat is much more like a mix of sandy soil types with clay, rocks, and shrubs. The soil layers in arid regions are called aridisols.

You can achieve this kind of substrate by mixing different varieties of reptile-specific brands together –   a staple formula usually given is 70% soil substrate to 30% sand-type, but you can add clay to give more structure to burrowing. Be mindful of soils designed to hold a lot of humidity as they will hold too much water for a dry bioactive environment (though you can put some in the humid hide area if you like). Many exotics brands have made their own specific species substrates, and some bioactive substrate blends. You can pick your favourite desert reptile sand substrate and mix with a suitable soil counterpart or go for a pre-made bioactive substrate which eliminates the guesswork.

Going for animal-specific substrates ensures safety – added fertilisers or treatments in everyday soils are often toxic. There’s a lot of potential for experimentation aligning with your desired aesthetic or texture.

These are images taken from Pakistan of natural leopard gecko habitat. As you can see, it isn’t the classic ‘sand dune’ desert image we may think of. See information on leopard geckos found in the wild in the scientific paper source of these images, by Muhammad Sharif Khan.

Plants

The plants in an arid bioactive setup are going to be quite different from a tropical one. They’ll be plant species adapted to periods without water and low relative humidity requirements, like succulents, cacti, aloe, and some airplants. There is a lot of choice in this area too! Here are just a few examples of arid-suited live plants that are commonly available:

• Ebony wax agave (Echeveria ebony)
• Zebra haworthia (Haworthia attenuata)
• Living stones (Lithops sp.)
• Socotra aloe (Aloe squarrosa)
• Burro’s tail cactus (Sedum morganianum)
• Short-leaved aloe (Aloe brevifolia)
• Snake plant (Sansevieria mikado)

These are just a few, many exotics brands now sell arid-suited plants for bioactive environments. Always check the suitability of the plant for animals, and beware of toxic plant species, like lilies and ivies – especially if your reptile is herbivorous.

Air plants, or Tillandsia, absorb their nutrients and moisture through leaves. This means they don’t rely on soil and can be positioned decoratively around the enclosure for added effect. This opens up more ways you can lay out your setup, especially if you don’t want to overcrowd the ground space too much. Here are some drought-resistant airplant species:

• Tillandsia tectorum peru
• Tillandsia xerographica
• Tillandsia gardneri
• Tillandsia paleacea
• Tillandsia diaguitensis
• Tillandsia duratii
• Tillandsia cacticola

Bring in the clean up crew

Now for the last essential part – the clean-up crew, or ‘custodians’ of your mini environment. For your bioactive setup to be self-maintaining, the correct invertebrates need to be introduced into the substrate and become established. In time they will break down animal waste and decaying plant matter, cycling nutrients to the benefit of everything, and reducing the amount of cleaning you need to do. Inevitably some of them will become snacks for your inhabitant (if they are an insectivore) but are generally good at staying hidden.

Well fed leopard geckos will reportedly ignore the soil invertebrates for the most part. Invertebrate cleaners that can tolerate a desert style setup include morio worms, Zoophobas morio  (and the adult beetles), springtails (Collembola) and isopods (Porcellio). You’ll often find these seeking refuge in the more humid parts of the enclosure, like under the water dish. Don’t worry if you hardly see them at all – they’re likely getting to work during the night.

Finishing touches

Now that the more technical parts are out of the way, you can add the rest of your essentials and decorations. Remember to provide plenty of hides, a humid place for shedding, an easily refilled water dish and a warm space for basking. Once you’re happy everything is established you can introduce your reptile and enjoy watching them explore their new environment.

In terms of maintenance, you will still need to spot-clean any waste from your animals, though this will gradually reduce over time with the help of the invertebrates in the soil. Fresh water should be provided regularly to prevent stagnation. As for the plants, they will appreciate infrequent misting, but being arid specialists, this will not be often – follow guidance for your specific plants. Eventually you may need to trim them back if they become a bit overgrown. Just feed your animal as often as they need, and wash the glass to keep your bioactive masterpiece in full view!

Going full bioactive ultimately allows you to enjoy your animals more by observing their natural behaviours, and having to do less maintenance and cleaning in the long run. Though it can be challenging to get going, your animals will certainly appreciate and benefit from this labour of love.