Bioactive Enclosure Crash Course

10/21/2024

What is a bioactive enclosure?

A bioactive enclosure is a set up in which microfauna (tiny animals), bacteria, and fungi are used to keep the enclosure clean. This drastically decreases how often an enclosure needs to be cleaned, however some people can find them tricky to maintain.

Environment

The first thing to consider should be what purpose is the enclosure for, what environment is needed, and if bioactive makes sense for the situation. Ask yourself:

  • Will it be dry or humid conditions?
  • Will it be heated or room temperature?
  • Does the animal have any skin/shell/scale issues that might be worsened?
  • Will the animal burrow

The set up for different environments can be very different so it is important to be aware going into the setup what the desired result will be.

Substrate

Some places offer commercial substrate mixes which generally work fine, but can be a little bit pricey. If you believe that is a fair trade off, commercial substrate might be a good option for you.

If you are interested in mixing your own substrate it is important to remember that every bioactive substrate needs at least two things: a base and a food source for the microfauna.

Note: Before you put anything in your substrate, make sure it has no added chemicals or fertilizers.

Tropical Substrate Base

A good base for tropical/humid substrates will help hold the moisture and give volume to the substrate. In most cases it will be the greatest proportion of the substrate. Some good options include things like coconut coir, peatmoss, cypress mulch, and sphagnum moss.

Additionally, it may be a good idea to add a drainage layer to prevent oversaturating the substrate. A drainage layer consists of a piece of mesh or screen over rocks/gravel/clay spheres/anything porous that won’t rot when sitting in water and will create a space under the screen. The idea is that the water will filter through the screen into the space beneath to prevent flooding and excessive bacterial growth. While not strictly necessary, you need to be very careful to avoid overwatering if you decide to go without it.

Arid Substrate Base

An arid/dry bioactive enclosure can be misleading since moisture is necessary for the waste to be broken down. one of the best ways to achieve this is to have two layers of substrate, a deeper one set up as a tropical substrate and a dry layer over the top. The dry layer can be things like coconut husk, sand, coconut coir, or gravel.

Note: sand and gravel should not be used if the animal is likely to ingest them as this could cause impaction.

Microfauna Food Source

While micro fauna will eat waste, discarded food, dead plants, etc. they do need plant matter mixed into the substrate for them, namely cellulose. This can be provided through woodchips/pulverized wood (avoid walnut, cedar, and conifers as they can be toxic), pressed paper egg cartons, or leaves. Leaves are generally considered the staple for most of the commonly utilized microfauna species so should always be available (again, avoid walnut, cedar, and conifers).

Extra Substrate Additions

Some other things that can be beneficial to add to the substrate are:

  • Fibrous materials like tree fern or coconut husk – The longer fibers will help maintain tunnels for burrowing species and maintain substrate aeration
  • Limestone sand/egg shell – Adds calcium to the substrate which can supplement microfauna and reduce substrate acidity (different plants and animals may prefer different soil acidity levels)
  • Activated charcoal – Can absorb some waste compounds in the soil
  • Sand – Sand can help improve drainage or reduce clumping of soil (generally more useful in arid setups)
Microfauna
Microflora

Microflora refers to any bacteria or fungi in the substrate. While technically not microfauna, the are critical to the health of the enclosure. While these microflora can be allowed to grow in the substrate naturally by just maintaining the substrate overtime, it is much quicker and more reliable to use a bioactive inoculant. If you allow the process to occur naturally it can take weeks to months for the microflora to reach a balance if it happens at all, whereas with a commercial inoculant it is still a good idea to give it some time to ensure no strange fungal or bacterial blooms occur but it is typically safe to use within the week. (Note: if you use a commercial inoculant that has different directions on how long to wait, follow them, they are more familiar with their specific product.)

Another option if you already have an established setup is that you can use that substrate as an inoculant for new substrate, however know that there is the potential for spread of disease or pests between enclosures with this method. I recommend that if you would like to use existing substrate to inoculate keeping an separate enclosure or bin that only houses the inoculated substrate.

Microfauna/Cleanup Crew

The microfauna aspect consists of tiny creatures, usually arthropods, that will consume waste and excess fungi/bacteria. There are many options available, some for sale, some that tend to just find their way int enclosures.

  • Isopods – Isopods are one of the most commonly bought cleanup crew animals. Pros: they tend to be better at breaking down larger waste, tend to be more photogenic, and may be able to serve as a food source for the primary animal in the enclosure. Cons: Depending on the species, they may be more sensitive to changes in the environment, may eat live plant, and may nibble on the primary animal. See below section for more details
  • Springtails – Springtail is a broad group of tiny arthropods that have a little tail that they can use to launch themselves with when startled. Pros: There are strains for arid and tropical setups, they do not harm other animals, they do not harm live plants, they are efficient at consuming mold, they are prolific, they are resilient. Cons: None
  • Soil Mites – Soil mites are not commonly sold intentionally, they tend to just spontaneously appear in soil. Pros: they do not harm other animals, do not harm live plants, and are very resilient. Cons: some people find them repulsive, they will crawl over other animals which can be stressful if there are a lot, if resources are limited they will compete with springtails.
  • Darkling beetles – I have known people to use darkling beetles in arid enclosures, but have not tried them yet.
Isopod Species

When it comes to clean up crew, not all species or morphs are created equally. Some options to consider:

  • Porcellio pruinosus (powder blue/orange) – These isopods are more arid tolerant than most, are highly prolific, do not typically bother other animals or plants in the enclosure, and look nice.
  • Cubaris ‘Panda King’- These isopods do not typically bother other animals or plants in the enclosure, they do best in more humid environments, they require a calcium source, they are more expensive than other options, and look nice.
  • Porcellio dilatatus (giant canyon) – These isopods are bigger than most of the others, they are voracious, they are prolific, they will eat live plants if other food is not available (and sometimes if it is), they could try to nibble on other animals, and they are large enough some lizards might try to eat them.
  • Trichorhina tomentosa (dwarf white) – These isopods are tiny, they may be eaten by small animals like dart frogs, they are too small to nibble on other animals, it is unclear if they affect live plants, and they burrow most of the time.

Note: Some isopods will have white or mostly white morphs, these isopods (with the exception of T. tormentosa) tend to be more fragile and sensitive to environmental changes so are not ideal in most enclosures.

Plants

A true bioactive substrate needs plants to help filter out some of the compounds that will accumulate in the soil (i.e. nitrates). The main considerations should be whether the plant is suitable for the environment and whether the plant is safe if consumed. Keep in mind that if the roots go down into the moist layer, non-arid plants can thrive in an arid setup. Also, if you buy your plant from a garden shop/nursery/etc. Make sure the plant is chemical free before planting it in the enclosure, either by washing it thoroughly or letting it grow out or both. Here is an incomplete list of safe plants:

  • Aeonium (Arid)
  • African violet
  • Blush aloe (Arid)
  • Bromeliad
  • Echeveria(Arid)
  • Nerve plant
  • Oat grass
  • Selaginella
  • Spider plant
Enclosure Upkeep

While a properly set up bioactive enclosure should do a decent job of keeping itself clean it does still need occasional maintenance. For one, water must be added to maintain humidity as it evaporates. It may also be necessary to supplement the microfauna’s food by adding additional leaves periodically.

At least once every 6-12 months, the substrate should be tested for ammonia/nitrate levels and/or replaced. This will ensure that the levels of these harmful chemicals are managed and will prevent harm to your animals. Note: when you replace the substrate, do NOT just throw it outside. That could introduce potentially harmful, non-native species to your environment. Before disposal dry, heat, or freeze the substrate to kill any microfauna.