FAQ: Enclosures for reptiles

Crested geckos do well on a moisture-holding substrate such as coconut fibre, a soil mix or a bioactive substrate with moss. They seldom come down to the ground, but the substrate helps maintain humidity.

Ball pythons are often kept on bark, coconut fibre or a mix of the two, as they hold humidity well. The substrate must not be constantly wet, as too much moisture can cause skin problems.

Tortoises do well on soil, or a mix of soil with sand or coconut fibre, which they can dig in and which holds some moisture. The substrate should not be dusty, and food is best placed on a tile or plate so the tortoise does not swallow substrate.

Many aquatic turtles need no substrate on the bottom, and a bare floor is easier to clean. If you do use substrate, choose fine sand or very large stones the turtle cannot swallow, as medium-sized pebbles are dangerous.

Droppings and soiled substrate are removed daily or whenever you notice them, and the whole substrate is replaced every few weeks or months depending on the type and the animal. In a bioactive terrarium the substrate is usually never replaced, only topped up.

Substrates sold specifically for terrariums usually do not need sterilising. If you use natural items you collected, such as leaves or stones, wash and treat them so no parasites or harmful substances get in.

A few grains swallowed by accident are usually harmless, but regularly eating substrate can cause a gut blockage. Put food in a bowl or on a tile, check that the animal is not short of minerals, and talk to a vet if the behaviour continues.

Mould appears when the substrate stays wet too long, ventilation is poor, or leftover food and droppings remain. Remove the affected part, improve ventilation, mist less often and clean the terrarium regularly.

Multiply the terrarium floor’s length and width by the desired layer depth; the resulting volume in litres shows how much substrate you need. Packs often state their volume, so it is easy to work out how many you will need.

Larger packs are often cheaper per litre, so they suit large terrariums or regular substrate changes. Compare the price per litre and make sure you have a dry place to store what is left.

Keep substrate in a dry place in a closed bag or box so it does not go mouldy and insects do not get in. Damp coconut fibre or moss is best used quickly or dried before storing.

A bioactive terrarium is a partly self-cleaning ecosystem with living substrate, plants and tiny invertebrates that break down droppings and food leftovers. It is closer to the natural habitat, but needs careful setup and upkeep.

A clean-up crew is made up of small invertebrates, most often springtails and isopods, that feed on organic waste and mould. They help keep the substrate clean and loose.

Yes, dry bioactive terrariums are set up for desert species using a drier soil and sand mix, drought-tolerant plants and isopods that tolerate dry conditions. Part of the substrate in the cooler zone is kept slightly damper so the clean-up crew survives.

A drainage layer of clay balls or other coarse granules under the substrate holds excess water so the soil does not rot. A mesh or fabric goes between the drainage and the substrate so the layers do not mix.

Plants that are non-toxic to reptiles and tolerate the conditions work, for example pothos, bromeliads or ferns for tropical terrariums and succulents and some grasses for dry ones. Before planting, check that the plant is safe for your species and wash off fertilisers and pesticides.

A bioactive terrarium needs cleaning less often, but large droppings, shed skin and spoiled food are still worth removing. The glass and water bowl also need cleaning, plants need trimming and the substrate occasionally needs topping up.

Waiting a few weeks is often recommended so the plants root and the clean-up crew multiplies. During this time you can also adjust temperature and humidity so the reptile moves into a stable environment.

Some lizards happily eat isopods and other small invertebrates, so their numbers may drop. To keep the clean-up crew going, leave hiding places under bark or leaves and top it up now and then if needed.

Dry leaves such as oak or beech are food and shelter for the clean-up crew, help hold moisture and give a natural look. Collect leaves from clean places far from roads and treat them before use.