The importance of lichen for isopods

Lichen is one of an isopod’s favourite treats, but it’s also packed with some genuinely impressive benefits.

In the wild, isopods are opportunistic detritivores. They feed on whatever decaying or microbe-rich material they encounter, including leaf litter, rotting wood, fungi, and biofilms. Lichen falls neatly into this category.

As lichen ages or begins to break down, it softens enough for isopods to graze on comfortably. Many species will actively rasp at it, consuming both the fungal and algal components that the lichen surface hosts. This is important, because isopods don’t just eat for direct nutrition, they also feed on the microbial life associated with their food. The complex biofilms that develop on lichen surfaces can play a role in supporting gut health, digestion, and overall microbial diversity within the enclosure. This can be especially beneficial for juveniles, which rely on constant access to food.

Furthermore, lichen is neither overly rich nor fatty like many protein-based foods or supplemental feeds. As a result, it does not disrupt the nutritional balance of the tub. This makes it ideal as a constant, freely available supplement rather than something that must be carefully rationed.

Beyond its nutritional value, the natural grazing and rasping involved in feeding on lichen encourages increased activity in isopods and provides valuable enrichment. Structurally, lichen-covered sticks and bark tend to retain slightly higher humidity, making them popular hiding spots and covers. This adds another layer of environmental enrichment and microclimate variation within the tub.

For anyone keeping Ardentiella species, lichen isn’t just a nice extra, I think it is absolutely essential to provide.

Whenever I offer freshly collected lichen, my Ardentiella immediately flock to it, spending the majority of their time gathered on it and actively feeding. In most cases, within a week they have consumed every usable portion. They don’t just nibble but strip it completely down to the bare wood. This strong preference suggests that lichen likely plays a significant role in their natural diet in Vietnam. In my experience, providing lichen results in increased activity and improved body colouration vs not providing lichen.

That said, lichen isn’t exclusive to Ardentiella. Other genera such as Cubaris, Porcellio, Armadillidium, and many more also enjoy lichen immensely, though their preference for it does vary species to species.

While most commonly encountered lichens are safe, it is best to stick to familiar foliose and fruticose lichens, the leafy and branching types typically found growing on tree bark and deadwood. These are the forms most frequently used by keepers and are also the most readily accepted by isopods. Safe, commonly used lichens are usually muted shades of green, grey-green, pale blue-green, or soft yellow-green. Foliose lichens form flat, leaf-like lobes that often overlap and peel slightly away from the bark, while fruticose lichens grow as fine branching tufts, threads, or small shrubby clumps.

Avoid collecting lichens with unusually bright or artificial-looking colours, or those with strong chemical or medicinal odours, as some species produce potent secondary compounds. When in doubt, it is better to leave it behind and collect only what you can confidently recognise as common woodland lichen.

Lichen can be provided as a long-term food source rather than a temporary treat. It can be left in the enclosure continuously and replaced once it has been fully consumed or has broken down beyond use.

However, while lichen is an excellent addition and I am singing its praises, it is important to note it should not replace core dietary components such as leaf litter and decaying wood. Instead, it works best as a permanent supplement that complements these staples and increases dietary diversity.

When collecting lichen, it is essential to do so ethically and with care for both the environment and your isopods. Never harvest lichen from protected sites such as SSSIs, nature reserves, signed parkland, or private land without explicit permission. Only gather lichen from clean, pesticide-free environments, and avoid roadside, urban, or industrial areas, as lichen absorbs pollutants extremely easily. Suitable collection sites typically include undisturbed woodlands, where lichen can often be found growing on tree bark, fallen branches, logs, and deadwood. Alternatively, lichen may be sourced from reputable suppliers.

Before introducing lichen into a tub, proper preparation and quarantining are strongly recommended. Freezing the lichen and/or soaking it in water helps eliminate any potential hitchhikers such as mites or small insects, without damaging its structure or nutritional value. Once prepared, the lichen can be safely offered as a natural and enriching food source.

There we have it. Lichen is far more than a simple supplementary food. It provides nutrition, enrichment, and habitat structure all in one. For certain species, such as Ardentiella, it is an absolute must, but in truth, offering lichen to all of your tubs is one of the easiest ways to improve their diet.

If you want to see your isopods truly thrive, add lichen and thank yourself later!