Introducing Bioactive and Naturalistic Principles to Your Rat Cage

Naturalistic & Bioactive Rat Cage

Creating a safe and interesting cage layout for your rats is relatively straight forward. However, a new movement in pet keeping is challenging whether the way we keep rats – in cages, on shallow substrates and with artificial toys such as wheels – is the healthiest and best way to look after them. 

Being able to exhibit natural behaviors in captivity is crucial to all animal welfare, and rats are no different. Rats can spend most of their day in their cage, so being able to run, dig, climb, forage, and exercise choice in their environment is essential to fully realized rattiness.

The natural and bioactive movement challenges us to look at whether our traditional cage set-ups really meet these needs.

What Does “Natural” Mean in a Rat Cage?

Natural can have two meanings in this context. The first is that the rats’ environment allows them to live an unrestricted life, able to exhibit their full range of natural and instinctive behaviors within their normal day to day activities. 

An alternative meaning refers not to the rats, but to their cage furnishings. Proponents of “naturalistic” rat cages prefer to remove all plastic, fleece and brightly colored materials from the cage and replace them with plant-based items such as hemp rope and fabric, bamboo, coconut shells, coir matting, and of course wooden branches and toys.

The first definition is the most important as it has the largest effect on our pets’ welfare. As long as a rat can express all its natural behaviors, then they aren’t affected by whether their ropes are undyed hemp or bright stripey cotton, or whether their perches are wooden or plastic. The only important caveat around cage furnishings from the welfare point of view is that the materials must meet the rats’ needs, be safe and non-toxic. Beyond that, it’s down to human preference. 

However, there are other reasons to look at natural cage furnishings – primarily their environmental impact. Rats might not care what their ropes are made of, but undyed hemp rope is likely to have a much smaller environmental footprint than brightly dyed cotton.

Similarly, plastic in animal toys, while not normally detrimental to the animal, is still plastic – it needs to be manufactured in an industrial process, and will one day be thrown away and contribute to long-term plastic pollution. The fleece fabrics routinely used in hammocks and cage liners are also made of plastic, and constantly release microfibers into the air and washing.

Personally, I’m not going to throw out all my existing cage furnishings – yes many of the baskets and boxes are made of plastic, and the ropes are cotton – but to throw them away at this stage would be even less environmentally friendly than owning them in the first place. I’ll use them and reuse them until they are no longer functional.

However, I am trying to be more aware in anything new I add to the cage – for example, in future I will most likely make my own ropes from undyed materials or old clothes, rather than buying new parrot ropes. I am also increasingly making my hammocks out of old t-shirts that are no longer fit to wear, rather than using fleece fabric.

So, I probably will move towards a naturalistic cage set-up, but it will be slowly, following the principles of reducing and reusing materials, rather than a sudden redesign.

Auditing Your Cage for Natural Behaviors

If the most important aspect of a naturalistic rat cage is a design that allows our pets to express their natural behaviors, the first question to ask is how well do our existing cage layouts stack-up?

Bioactive rat cage
Naturalistic rat cage setup by Isamu Rats

Crucial natural behaviors are…


This is really important for rats as it maintains muscle strength in their upper bodies, as well as helping them retain skills in dexterity and balance into old age.

Opportunities for climbing can include:

  • ropes,
  • branches,
  • cage bars,
  • spaced out ledges or perches,
  • as well as “climbing frames” (I use an old wooden wine rack).

However, ladders don’t count – they aren’t physically challenging enough.


Rats need aerobic exercise just like we do. They also love to run and boing about when they are excited or playing. Many rats only get a really good run around outside their cage (this is one of the reasons I now keep my rats in a safe 24/7 free-range room instead), but a cage with a good sized footprint and multiple levels can still allow rats plenty of exercise.

Large wheels can also be useful, although some rats just ignore them.


Most wild animals invest the majority of their time awake in looking for food. As a result, animals in captivity can get bored easily when their food is delivered in a bowl.

To stimulate foraging behaviors, hiding food around the cage and scatter-feeding dry mix in the substrate can help, as can puzzle toys and different ways of presenting food such as kabobs and pinatas.


Rats love making nests, and whilst they will make them out of anything handy, they enjoy it more if they have choice – about where to sleep and what to build their nest out of.

A good cage layout should offer a range of places to snooze, and a range of options for bedding, from newspaper and kitchen tissue, through to bits of fabric, substrate such as shredded cardboard, safe shavings, hay, and even things like dry sheep’s wool.

Providing materials in such a way that the rats have to tear them up, move and process them themselves is also beneficial intellectual stimulation. My horde are currently working on a nest made out of a pair of sacrificial curtains. They’ve taken about a foot off the bottom so far.


Digging is often an overlooked behavior for pet rats. We provide tubes they can hide in, and sometimes a shallow substrate for foraging, but forget that in the wild, Rattus norvegicus is a mostly ground living animal that builds complex burrows.

A good cage layout will provide the opportunity with a base layer of thick substrate, or with a large digging box. However, now we are starting to question whether the normal cage bases we give our rats (often only 10-15 cm deep) are actually enough, or whether we need to rethink how we enable them to dig altogether. That’s where the bioactive part of “natural and bioactive” comes in.

What Is a Bioactive Rat Cage Set-up?

Rat Cage Setup
Bioactive Rat Cage Setup by Dyana Tetreau

One of the problems with traditional substrates like kiln-dried shavings, hemp, or shredded paper is that they aren’t that good at holding burrows. Rats can dig down, but they can’t build their own subterranean kingdom. Conventional substrates can also be dusty, and, if the rats pee on them, can get smelly quite quickly.

The bioactive approach solves these issues by using a sterile coco soil that is kept slightly damp. The soil moisture damps down dust and allows the soil to retain its shape as the rats create burrows. A soil substrate also offers the opportunity to add in rat-safe plants – although in my experience they don’t tend to last very long once the rats get at them.

However, the soil itself isn’t the bioactive bit – that comes with the clean-up crew (CUC in bioactive care shorthand). These are rat-safe invertebrates like springtails that live full-time in the soil, and take care of cleaning up mould, stray food and poop. Together, the soil and the CUC create a self-cleaning substrate that can be safely left in place for months. 

Of course, a bioactive set-up does require a few extra steps to get going – the most important is a deep enough base, as rats will kick the soil everywhere if there is not enough containment. Most owners who want to go bioactive build their own deep bases out of perspex – transparent walls have the added advantage of allowing a view into the burrows.

It is also important to understand that having a clean-up crew doesn’t relieve owners of all their housekeeping duties. It is important to:

  • keep the soil slightly moist (dry soil is dusty and bad for the rats and the CUC),
  • and to turn it at least once a week to prevent ammonia build-up in the tunnels.

This is really important to prevent the rats getting ill with respiratory disease. It is also necessary to still have litter trays, and to clean the rest of the cage regularly. However, with some investment in the set-up and responsible husbandry, a natural and bioactive cage setup offers a rewarding new take on rat care for rats and owners alike.

Want to learn more? Check out the Naturalistic and Bioactive Rat Set-ups group on Facebook. With over three thousand members it’s a brilliant resource for ideas and all your questions about how to get started.

Here’s a bioactive / naturalistic rat cage setup in action!

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  1. What about the branches and leaves/plants in the cage? Is it safe to simply pluck these from the outdoors? Or is there a cleaning process to prevent parasites and unwanted chemicals (like pesticides) from entering the cage through these items?

    1. For me it was Allegro – so you can just order online, if it’s hot enough outside to not kill them during the travel (so not minus Celsius temperature at least). Other than that pet stores, that are terrarium friendly – so some of them, that are more focused on lizards, snakes, insects etc.

  2. Would you recommend impregnating the wooden ellements with, for exaple coconut oil, so they wont absort urine?

    1. I don’t impregnate my wood – we just give it a really good scrub with F10 now and then. You could ask on the Naturalistic and Bioactive Rat Setups facebook page whether their members use anything.

  3. Would worms work too?? For a bioactive set up and can you use regular soil or could I get stuff from outside ??

    1. Hi Lizzie,
      Worms would get eaten very quickly so not usually worth the cost. It would also be important to use sterile worms bred for bioactive settings, as normal garden ones could carry parasites. Similarly, soil needs to be sterile coco-mulch (sold for reptiles and also (usually cheaper) in garden centres – just get the one without any additives). Garden soil can carry all sorts of disease microbes and parasites such as toxoplasmosis.

  4. Is it possible to use a plastic storage bin instead of acrylic? That kind of thing is a bit too expensive for me at the moment. Might upgrade in future but for now it’s quite a bit above budget.

    1. Hi Jonathan,
      Sorry for taking such a long time to see your comment. Yes, I use plastic storage bins a lot as digging boxes. If used in a cage its important to check that rats can’t get trapped in any narrow areas around them, but otherwise the only downside is that some rats think they are chew toys…

  5. I’m doing this with the Brown rats I catch around the garage as a means of pest management. I sex and separate males and females into two separate colonies so that their numbers don’t increase and then let them live out the rest of their natural lives. I am using backyard soil,however, as this is the normal habitat for the wild rats I am catching. Its about 1-2 feet deep and they do love to burrow.

    As of now I have 6 females and 5 males who were caught just out of the nest about 6 months ago. I’m also keeping them in a secure structure outside that I built and am constantly upgrading. Only 2 have died from illnesses so far since I’ve had them, the rest seem pretty healthy and vigorous.

  6. hi! i keep my rat cage in my bedroom but i’m interested in starting a bio cage, would the springtails get out of the cage and infest my room? or is it not a concern?

  7. Hi, I see where many people have modified the critter nation storage shelf as an extension of the enclosure but I have not seen any tutorials on how this is done. Any links/instructions? Thank you!

    1. Hi, there are two common options that rat owners use. The first option is to add a large cement mixing tub measuring 24×36 inches, which equals the Critter Nation’s floor space. Some find they need to trim the tub before placing it inside the cage, while others simply push it in as is. This can be purchased at Home Depot, Lowe’s, or ordered from a smaller local hardware store. The second option is to purchase a large sheet of plexiglass, cut it to size (some hardware stores will cut it for you), and then glue the pieces together. There is a video on how to do that here: https://www.youtube.com/watch?v=HnlXxd9Snp8&ab_channel=IsamuRatCare . I hope this helps!

    1. Hi, according to IsamuRats, that is bamboo and her rats are not interested in eating it. It lasts for a few days until they remove the leaves, and then it needs swaping with a new batch.

  8. Hey, so i had a question i recently went to IKEA and got a basket made out of woven sedge(?) I can’t find any sources that say it’s safe for rats. Is it safe for me to put it in they’re cage?

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