The standard dimensions of a terrarium for an adult L. fulica are 30x40 cm. This can serve as a starting point for determining the appropriate size of terrariums for larger or smaller species, although every breeder has their own preferences and methods.
For terrestrial snails, a horizontally spacious enclosure will suffice, while arboreal snails will need more height than width. I do not recommend glass terrariums, as they do not retain enough heat and humidity. The best alternative is plastic boxes, which should be equipped with adequate ventilation.
The most important part of a gastropod terrarium is undoubtedly the substrate. Many people insist on using coconut fiber, but it’s not nearly enough. In fact, you’ll need to add dry leaves, rotten wood, twigs, or white wood pellets—and, if you want to be a perfectionist, cricket meal or legume meal.
Snails, being detritivores, very often feed on detritus itself: the substrate we place in the terrarium, where various elements decompose and release bacteria. Without this nutrient-rich detritus, an important part of their diet is missing.
There should be plenty of substrate—roughly five fingers deep—but the more, the better, as this allows the snail to burrow and helps the terrarium retain moisture more effectively.
There are many natural elements that can be added to achieve the desired nourishing effect:
Branches, bark, and leaves from maple, birch, beech, magnolia, cherry, plum, almond, peach, and oak trees
Acorns and acorn caps
Magnolia pinecones
Dried petals from magnolia, rose, hibiscus, and sunflower
Alder cones
Lotus seed tips
Coconut endocarp
Care must be taken to collect them ethically and sparingly, from the ground and from areas free of pollution or pesticides. Furthermore, before being placed in the terrarium, they should be boiled and allowed to dry to eliminate the risk of introducing potentially harmful parasites or fungi into the habitat.
In addition to the substrate, you can add hiding spots such as upturned bark, upside-down soft nursery pots, or—even better—live plants. Not all plants can be used, as some are toxic, and snails will eat anything they find in their path. Here are some plants that have worked very well for me:
Asparagus setaceus plumosus
Nephrolepsis exalta
Dracaena sp.
Peperomia sp.
Pothos (yes, it contains oxalic acid, but in minimal amounts. A slice of cucumber potentially contains more oxalic acid than an entire pothos plant)
Placing water bowls in the enclosure benefits the animal, as it can drink if it becomes dehydrated; however, these bowls must be made of food-grade silicone or soft plastic to prevent shell breakage in case of accidental falls.
Maintenance can be kept to a minimum by introducing a colony of scavenging invertebrates, such as Porcellio laevis or springtails, which will break down the gastropod’s waste and remove any leftover food. In this way, you’ll only need to make sure to mist the terrarium to maintain a nearly constant humidity level between 70% and 80% and to feed the snail.