Housing: Bioactive vs. Sterile

by Anthony Caponetto

The above photo of a group of gargoyles was taken as I was setting them up in a sterile style breeding enclosure.  

Breakdown of our sterile setup above:
The egg carton you see geckos climbing on is used as a ground covering, in place of natural leaf-litter, which also aids in retaining moisture after an enclosure is misted. The nest box in the back gives them multiple places to hide, both inside the box and in the crevices around it, between the box and the cage walls.  The dishes remain out in the open, at the front of the enclosure, for ease of replacing food/water/calcium.  Everything except the dishes, nest box and enclosure itself are replaced at each cleaning.

This setup was designed to replicate the sterile housing setup employed in an off-display breeding program at a highly regarded zoo, which happens to be well known for their reptile collection and also for their contributions to reptile conservation. They were incredibly successful at breeding a substantial number of reptiles as part of a conservation program, which is ultimately what made me decide to try tweaking their setup for our use.  While it's far from aesthetically pleasing, it has worked exceedingly well for the gecko species we house in it.  

Objective of this Article

The objective of this article is to simply explain the advantages and disadvantages of each type of housing, but is not meant to be a complete guide to them.  It assumes the reader is at least somewhat familiar with both types of housing. The primary goal is to inform the reader and combat the misinformation often seen on social media, so that the reader can make an informed decision on the type of housing that best suits them and their animals.

Full Disclosure

Before we dive in, I want to disclose my particular situation, so that readers understand my point of view and also see that I have no ulterior motive to recommend one over the other.  Before you listen to anyone's advice, it's important to know where they're coming from, what their actual (real world) experience level is and whether or not they have any reason (such as financial motivations) to be biased.

• I have always maintained my crested geckos and gargoyle geckos in sterile housing setups.
  I have always used sterile housing for crested and gargoyle geckos, starting with the first geckos I bought as a hobbyist in the early 2000’s.  We'll get into why as you read on, but suffice it to say it had nothing to do with having a large collection at the time. I just wanted to replicate what I had seen in the off-display breeding collections of zoos I had been allowed to tour.

• My personal collection is housed in naturalistic or bioactive setups.  
  Every snake and gecko in my personal collection today (which are mostly non-breeding animals at this point in my journey) are kept in naturalistic housing.  These enclosures absolutely have their place in my collection.

• I like both types of housing and will often recommend one or the other to my customers, depending on their collection, goals and particular situation.
  
  
• I do not believe either way is inherently superior. 
  I do however believe either way can be superior in certain situations. Both types of setups have their place in my collection and one or both may have their place in yours.

• I sell geckos. I do not sell caging or supplies of any kind.
  As such, I have zero financial incentive to recommend one type of housing over another.  I only want my customers to be properly informed and have the best experience possible, so they'll fall in love with this hobby and enjoy their geckos (and hopefully buy more!). I honestly couldn't care less which type of housing someone chooses, so long as they’re not being manipulated into choosing a setup that's not in the best interest of them or their geckos. 

Bioactive Housing

This is a methodology that started gaining popularity with hobbyists in the early 2000's.  The idea with bioactive housing is to set the cage up so that it doesn't need to be thoroughly cleaned on a regular basis, and instead relies on a miniature ecosystem of sorts, consisting of small insects (isopods) and a buildup of non-harmful bacteria to maintain a healthy environment for the geckos.  

Advantages

• Natural Appearance
  Make no mistake, these cages look awesome. For my personal taste, a naturalistic or bioactive setup is the only choice for a reptile cage on display in the home or office.  That being said, you need to understand this natural appearance is only an appearance, and it only serves the keeper's benefit and preference, not that of the geckos.  

• Less Regular Maintenance
  Because there are insects (isopods) utilized to remove waste in these setups, it's generally not necessary to replace substrate on a regular basis, but it is necessary to stir the top layer of soil on a regular basis.  On a smaller scale, it can be easy to maintain these cages and keep them looking nice, once they're properly set up. 

Disadvantages 

• Potential for Bacterial and Fungal Growth
  While small numbers of these cages can be easy to maintain, there's always the possibility of having mold or bacteria get to harmful levels before it is noticed - particularly if you don't know what you're doing.  Without proper drainage layers, ventilation and humidity levels and a healthy population of isopods, etc., these cages can become a breeding ground for mold and bacteria. The most common issue I see is when people don't stir the soil frequently enough, and they end up with actual mushrooms or a layer of mold covering the surface of the substrate.
  
  If you know anything about mold, you know it can spread throughout a room quickly, contaminating all cages in the room, making bioactive setups less ideal for larger collections.  These cages are time consuming to set up and it could be problematic having to disinfect and restart large numbers of them.
  
  It's important to remember that in nature, reptiles can simply leave and find a different microhabitat. In captivity, they're quite literally being held captive in the area that you've provided for them.  That being said, care must be taken to ensure the environment you're providing is free of harmful pathogens.

• Difficulty Controlling External and Internal Parasites
  While "natural" sounds nice, you need to remember that parasites occur in nature more often than in captivity.  These parasites are inherently more difficult to control in a bioactive cage.
  
  I once toured the collection of a vocal proponent of bioactive housing and soon noticed that literally every gecko in the collection had mites (external parasites) crawling on them.  The owner readily admitted to being unable to eliminate them, as it was a large room full of bioactive enclosures that would take months to disinfect and set back up.  His opinion was that they were natural and they didn't seem too harm his geckos.  To each his own, but I come from the snake world, where mites are avoided like the plague.  I would worry too much about geckos developing anemia and also the spread of any potential pathogens.
  
  Another issue is that, if the soil substrate isn't regularly stirred like it should be, fecal matter can accumulate on the cage floor. This leaves the geckos exposed to higher concentrations of bacteria and the eggs of internal parasites than they would normally in the wild.  I think it goes without saying that unhealthy levels of bacteria and parasites should be avoided.
  
  Bottom line, bioactive housing should not be seen as a maintenance or risk free method of housing reptiles. 

• Expense
  These cages are typically more elaborate and can be considerably more costly to get started and maintain.  For a cage in your office or living room, who cares - it's well worth the small investment.  For a larger collection, it can be cost prohibitive and impractical.  There's a large subset of our industry that revolves around the sale of bioactive supplies, so keep that in mind when listening to advice.

• Difficulty Retrieving Eggs
  This was the determining factor in my preference for a sterile setup for geckos that bury their eggs. Crested geckos and gargoyle geckos bury their eggs when laying them, which is a problem if you're using soil as a substrate.  In a planted terrarium, it gets even worse because you'll have roots to contend with.  Planted or not, you will almost certainly have trouble finding eggs with a soil substrate.  This can result in eggs not being found in time - which means either eggs end up dying or geckos end up hatching in the cage, which will then be eaten by the adults.  There's simply no foolproof way around this.  I have other gecko species that are egg-gluers (which adhere their eggs all over the cage) that we house in bioactive cages, but I'd personally never try breeding anything that buries eggs in a bioactive setup.

Misconceptions

• Reptiles are "happier" in this type of setup, making it more ethical.
  In my opinion, this is an assertion rooted in ignorance, and something I've only seen very obviously uninformed/inexperienced people claim to be true...often times, as they're trolling others on social media in an effort to project an image of being superior in one way or another. 
  
  I have seen zero evidence, nor have I ever heard a convincing argument to suggest reptiles are more happy in a bioactive setup, or less happy in a sterile one.  If you believe this to be the case, you may lack a basic understanding of how a reptile's brain works in relation to that of a bird or mammal, and you're probably making the mistake of anthropomorphizing - putting human thoughts and emotions on an animal that simply doesn't think like a human.
  
  The reality is that reptiles don't care if you put foliage or dirt in the cage or not - they're going to climb through it, hide in it and defecate on it without any consideration of how pretty you think it is.  Yes, I put this same point under both types of housing because it bears repeating. 

• It's more "natural".
  While it may appear natural, the reality is you're still confining wild animals to a box - regardless of how it's decorated or how many bugs and plants you put in that box.  Unlike in nature, geckos in captivity are effectively trapped in the enclosure you house them in, which means they'll be unable to choose a different microhabitat or get away from pathogens that may harm them. 
  
  If you want your reptiles to live truly natural lives, you'll need to send them back to their wild range, where they'll probably be eaten by a bird and live a fraction of the time they would have in captivity. :-)

Sterile Housing

Practicality and disease prevention is the name of the game here.  This methodology is popular in commercial breeding collections, the off-display breeding collections of most zoos and in academic or scientific institutions, where their biology is being studied. 

The sterile setup we use for our gecko breeding collection is actually modeled after similar setups that I've seen when touring the off-display breeding collections of zoos, the names of which I won't disclose here.  (They did me a favor by letting me see their breeding programs. If I put their names out there, the ignorant "moral crusaders" I'll talk abut below will try to tarnish their reputations and I'd never be invited back).

These cages typically employ paper substrates, but you may also see particulate substrates like shredded or chipped wood products, coconut fiber and others, depending on the species and whether or not animals are being bred or simply kept for study.  These cages typically employ unnatural-looking nest boxes, hiding areas and food/water dishes with smooth surfaces that can be easily disinfected.  Various inexpensive, disposable items that can simply be replaced periodically are also utilized. 

Advantages

• More Sanitary, Easier to Clean Thoroughly
  The primary advantage of a sterile setup is it's very easy to completely disinfect the entire environment, which is a must in larger collections, where the risk of spreading pathogens could be devastating.  This is a big reason why it's the choice of zoos for their off-display animals, including the breeding programs they have for various conservation efforts.

• Less Expensive
  This type of setup typically consists of a plastic tote for a cage, which are often kept in a lidless rack system. These setups are generally more cost-effective, as fewer supplies are needed.

Disadvantages 

• Unnatural Appearance
  This is probably the biggest drawback for most hobbyists - no one loves looking at a floor covered in paper and plastic items. These setups tend to look very plain and they aren't going to look impressive in your office or living room.  While some don't mind it, I personally wouldn't consider a sterile housing setup for display in my home.  That being said, there's nothing to say you can't add foliage, plants and more natural looking items to a sterile type of setup.  With a little ingenuity, it's entirely possible to design a sterile setup that looks fairly naturalistic, without going full-on bioactive.

• Difficulty Controlling Humidity
  Because these cages don't have layers of soil and drainage media, they generally need to be misted with less water on a more frequent basis.  They can be less forgiving when it comes to humidification because they lack the layers of substrate and drainage media off a bioactive setup. The lack of natural drainage can lead to too much moisture collecting on the floor of the cage, which can result in mold if you're not careful.  Just as with a bioactive setup, this situation makes it necessary to disinfect the cage and replace the substrate, but that's much easier with a sterile setup.

Misconceptions

• Reptiles are less happy in this type of setup, making it unethical.
  In my opinion, this is an assertion rooted in ignorance, and something I've only seen very obviously uninformed/inexperienced people assert...often times, as they're trolling others on social media in an effort to project an image of being superior in one way or another.
  
  I have seen zero evidence, nor have I ever heard a convincing argument to suggest reptiles are less happy in a sterile setup.  If you believe this, you may lack a basic understanding of how a reptile's brain works in relation to that of a bird or mammal, and you're probably making the mistake of anthropomorphizing - putting human thoughts and emotions on an animal that simply doesn't think like a human. Reptiles don't care if you put foliage in the cage or not - they're going to climb through it, hide in it and defecate on it without any consideration of how pretty it is.  Yes, I put this same point under both types of housing because it bears repeating. 
  
  As long as the animals aren't suffering, there is no basis for such assertions.  If a sterile cage setup was truly unethical or was in any way bad for the wellbeing of the reptiles, this style of housing wouldn't be employed in the off-display breeding and conservation programs of so many world-renowned zoos. 

Deciding Which is Right for You

Consider YOUR Circumstances and Choose What's Right for You.
My opinion on the matter is that each method of housing geckos works well, but one is usually better suited for each individual's particular situation.  Which one is better completely depends on the keeper and their situation.  There isn't one "right way" to house reptiles, and if anyone tells you that, I can guarantee you they're not as experienced as they want you to believe. 

If you have a smaller collection, particularly one kept in the main living area of your home, you may better enjoy housing your collection in bioactive setups.  If you have a lot of geckos and you don't care about aesthetics, you may find your geckos do better in a sterile setup.  Another point worth mentioning is I've seen plenty of setups that are essentially a hybrid of the two....more sterile in function, but more natural in appearance.  As long as the animals stay healthy, you should always do what works best for you. 

Always Consider the Source When Seeking Advice
As with anything, you should always consider the source when seeking out advice.  There are two types of people, in particular, that promote bioactive housing as the only way of keeping these geckos, and I try to caution customers about both.  I'll just come out and put them on blast without the sugar coating here... :-)

• Those with Financial Motivation
  There's an entire subset of the reptile industry that revolves around the sale of bioactive housing and supplies. There's a lot of money being made selling the required supplies, such as bio-balls for drainage, plants, isopods, glass enclosures and all kinds of other things that go along with it. 
  
  If someone is in the business of selling bioactive supplies, then they have a financial incentive for you to believe that's the only good option for you or anyone else.  They may even go so far as to make assertions that a bioactive setup is the only ethical way to keep these geckos.
  
  It's easier to make money selling supplies and dry goods than it is to breed reptiles.  Big pet chains have known this for years and have done a great job selling unnecessary junk to newer reptile owners.  This trend has been carried over into our hobby in the past 20 years or so and there are a ton of show vendors and gecko breeders who sell bioactive supplies.  There's absolutely nothing wrong with that until they start throwing stones at people who don't, and trying to manipulate the general public into thinking they must buy into the bioactive concept, in order to be an ethical reptile owner.
  
  These people are always going to have a biased opinion on the subject, they're never going to have a pragmatic or practical stance and the advice you receive from them should be taken with a grain of salt.   "Don't ask the barber if you need a haircut" is an anecdote that absolutely applies here.  

• Wannabe Experts & Moral Crusaders
  These are people who typically have no financial motivation, but rather want to project the image of being an expert or to be seen as morally and ethically superior.  This is typically limited to social media, where they can easily get away from a conversation that isn't going their way - they tend to be more humble in real life because they can't use Google to help them sound more knowledgeable.  These people will often react as if their expertise is being challenged or threatened by anyone or anything that might contradict the advice they've been handing out. They will often react by hurling accusations of unethical treatment of animals, greed, etc.  
  
  Because they're uninformed (or have been misinformed), they lack the requisite knowledge to understand that there is no one "right way" to do this and they usually know little to nothing about how zoos and professional breeders house their breeding animals.
  
  These people are often uninformed or misinformed, and their base of knowledge is usually limited to what they've read or been told - which they will then irresponsibly pass on to others, as if they're stating a set of known facts.  As is the case with pretend-experts in every walk of life, if you're familiar with the subject matter, it quickly becomes apparent that they're not as experienced as they want people to believe.  If you're new to this, however, it can be difficult to differentiate the professionals from the posers. 
  
  If these "helpful" people on social media actually cared about other keepers or their animals, they wouldn't be handing out advice without the real-world experience to know if it's sound or accurate. They have no business hurling accusations at the professionals, who actually do know what they're doing, or those following the advice of said professionals.
  
  Bottom line, don't be fooled. The reality is that most of these folks are just trying to project a certain image and they often have no real clue of what they're talking about. 
  
  Do your homework, think for yourself and then make an intelligent, informed decision that's right for you and your collection.