Many care sheets and information pages talk about using custodians to create a nice natural bio-active set up - but what is that, and why should you want to do it? Let’s look into it, and see what all the fuss is about.

Custodians are small creatures that live in your reptile enclosure, and basically break down the waste that is produced there. That’s right. They break down and consume all the bad stuff – decaying plant matter, leftover food, animal waste, fungus, and other bacteria’s that build up in the substrate. They basically keep it clean for you. That’s got to be a winner, right?

There are many types of custodians, and different creatures will perform slightly different jobs, so a good selection of these is the best way to ensure your reptile environment is kept at its best. But it’s not just as easy as throwing them in and not cleaning it out again – they also each have their own requirements that you’ll have to fulfil in order for them to thrive, and therefore do their required job. So, what bugs can you get?


The most common friend you can add is the Springtail, which you’ll buy in a tub of soil, and there will be thousands of little creatures in there to get you going. These are a small white creature, thinner than a grain of rice, but similar in length. They particularly like to eat mould and faeces – lovely!

Although there many look to be plenty, Springtails will often need the time to establish themselves in an environment before an animal is put into it, otherwise they don’t have a chance to populate enough to control the waste that’s produced. This is particularly important for small species, such as small lizards or frogs, which will see the Springtails as a food source as well, so they really need to be established well before your frog starts munching them all. Two weeks is usually sufficient time to start a colony before adding your animal.

Springtails require warmth, of around 25C. In most environments you should be running a hot end and cool end – they will move to suit themselves, just as your reptile will, so don’t worry about this overly. The main thing with them is to ensure they have adequate humidity, as they cannot thrive without it. This is why they tend to be so popular in rainforest enclosure, such as frogs or day geckos. You can keep them in drier desert enclosures – keep reading to find out how.


Another popular choice of custodian is the Tropical Woodlouse. These can be harder to come across, but these small crustaceans have very similar requirements to Springtails, and are often housed together because of it. They will thrive particularly well with the use of leaf litter, ensuring that there are plenty of dark places for them, which they like to be damp and humid. Woodlice feed on organic matter, so decaying plants and animal waste is ideal for them.

There are many different species of woodlice available, so they are hard to describe as a whole, but commonly they will be slightly larger than your Springtails and probably white as well, though a grey species is also common. They will also be sold in tubs of soil, and as they are slightly bigger, will be a more obvious food source for you reptile, so ensuring lots of hiding places, and that important time to establish in advance of an animal arriving, it vital to keeping these creatures.


A popular choice is Darkling Beetles – the adult form of mealworms. Through some mealworms in and they’ll turn into beetles eventually, not before scoffing through some waste, as well as turning up the substrate quite well, which will help to keep bacteria levels down. These can live in a much better range of environments, and will easily take a dry arid enclosure, as well as a more humid rainforest set up – an ideal addition. Large numbers can be required though, as this larger creature is an easy to munch food source.

Another option is Earth Worms. Commonly available are Dendrobaena Earth Worms, a small compost worm which will move through the substrate move effectively, preventing stagnant areas and ensuring waste is turned over, and specifically eating waste – so faeces mainly. They will also come in a small tub of soil, best just to dump the whole thing in, and let them the time to burrow and hide before your reptile is introduced. They do particularly well in higher temperatures, and so are great for reptile enclosures. Often offered alongside these are Lubricus Worms – these are much bigger, and are more commonly used as a food source, as they don’t tend to do well in the warmer temperatures. Better to avoid these, or just put in occasionally as food.

A final species to look at, which are better suited to the drier environment, would be the Dermistid Beetles. These are the adult form of the furry little worm you see scurrying around with your crickets. The worm form tends to be the most effective, and can east just about anything – they are often used to clean skeletons in fact! The adult beetle stage do tend to stray more towards greenery for food, but the little furry friend can be very efficient, and more importantly, do well in your dry, arid, desert environment. So when feeding your Bearded dragons, just chuck the furry worms in too!

Ok, so now you have an idea of what species, or group of species, that you want to use. Now you need to set up for them. As we’ve seen, most of these require humidity and warmth. Warmth should already be ticked off, as the basic requirement for your reptile, and for any rainforest enclosures, that’s also already there, ensuring your reptile itself is happy and healthy. However, the best way to provide this is by the use of a reservoir layer, or drainage layer, underneath the substrate. This will always be able to provide water to the above substrate then, and mean it is always damp, without becoming waterlogged, which is very important.

The best way to create this is through the use of Hydro Rocks, a small ball that is often natural and formed from blown clay. This set up is best done in a glass terrarium, as its water tight, though a wooden vivarium could be adapted by the use of Perspex inside.

You place a layer of the balls on the base of your terrarium, covering to around 2” deep. This will become your water reservoir. To prevent the substrate mixing into this, a protective layer is needed. Hydro mesh or fleece is a good choice. Cut this to size and place over the balls, ensuring there are no gaps at all for substrate to fall through. On top of this, place your desired substrate – this can be soil, earth, sand or any mixture, whatever your species requires. Slowly poor water throughout the habitat, and watch it soak through and fill the reservoir underneath. Ideally, aim to have the reservoir always filled at least halfway. As the terrarium heats up, this water will be drawn upwards into the substrate, keeping it damp enough for your custodians to thrive. Even in a dry environment of sand, it is natural to have a water source underneath – think of sitting at the beach, and pushing your hand deeper and deeper into the sand, you can feel it becoming cooler and damper the further you go. This layout will recreate this natural environment perfectly. To finish, simply place your chosen decoration, and ideally live plants, which will also thrive with this water source underneath them, and also leaf litter, which will provide decaying matter eventually, as well as hiding places. Add your custodians, and allow to establish before introducing your reptile.

In order to maintain this, simply ensure there is enough food and water. Additions of food can help if needed, such as fish food or vegetable matter. The main thing then is to not disturb them too much – don’t go emptying it out all the time. Just let them do what they do best.

You can learn more about exotic animal care in our blog, try our Royal python care sheet to get started.