Bedding and substrate

Is this bedding safe?

Softwood shavings and raw corncob are still on shelves and still recommended by shop staff. This is the mistake that gets made before the animal even arrives.

Every bedding and substrate table

Safe, with a caveat, or never — for each kind we have built a table for, and a general list per category for the rest. These are material judgements rather than brand reviews: there are no product names anywhere on this site, so match the generic description to what the label actually says.

Hamsters

Depth is the whole point. A hamster with 25 cm of paper bedding behaves like a different animal to one with 3 cm.

Safe

Dust-extracted paper bedding, 25 cm deep or moreDeep enough to hold a tunnel that does not collapse. This is the single biggest enrichment change you can make.
safe
Kiln-dried aspenMixes well with paper to give the burrow structure.
safe
Plain chinchilla bathing sand in a heavy dishFor coat condition. Sand, never dust.
safe
Hay and plain toilet paper for nestingSafe nesting material a hamster can shred itself.
safe

With a caveat

HempGood absorbency, but on its own it does not hold a burrow. Mix with paper.
with a caveat

Never

Fluffy cotton-wool nesting materialWraps around limbs and is swallowed. Repeatedly implicated in limb injuries and blockages in hamsters.
never
Pine and cedar shavingsAromatic phenols; airway and liver damage.
never
Raw corncobBlockage risk, and it moulds.
never
Scented beddingThe hamster's nose lives in it.
never

Read the hamster care guides →

Rabbits

Rabbits need a clean, dry, non-slip floor plus a separate deep litter tray. The two jobs need two materials.

Safe

Paper-based litter in the tray, topped with hayRabbits eat while they toilet. Hay over paper litter serves both habits.
safe
Fleece or washable mats on the living floorNon-slip, warm, and washable.
safe
Straw for outdoor warmthInsulating, and different from hay: straw is bedding, hay is food. An outdoor rabbit needs both.
safe

With a caveat

Wood pelletsVery absorbent in a tray, uncomfortable underfoot as a floor.
with a caveat

Never

Clumping cat litterSwallowed while grooming and eating, and it clumps internally.
never
Pine and cedar shavingsAromatic phenols; airway irritation in a species already prone to respiratory disease.
never
Wire mesh floorsCauses sore hocks. Rabbits have no protective pad on the underside of the foot.
never

Check and clean the rear daily in warm weather. A soiled or damp rear is what flystrike needs.

Read the rabbit care guides →

Guinea Pigs

Guinea pigs do not burrow, so the priorities are absorbency, dryness and grip.

Safe

Fleece liners over an absorbent layerPopular and comfortable. It only works with absorbency underneath and a wash every few days.
safe
Dust-extracted paper beddingThe simplest reliable option.
safe
Deep soft hay over an absorbent baseFood, bedding and cover at once.
safe

With a caveat

Kiln-dried aspenSafe, but less absorbent than paper for an animal that produces a lot of urine.
with a caveat

Never

Pine and cedar shavingsAromatic phenols; respiratory irritation in a species with fragile lungs.
never
Sawdust and very dusty beddingGuinea pigs are prone to respiratory infection, and dust is a direct contributor.
never
Wire mesh floorsCauses sore hocks and trapped feet.
never

Read the guinea pig care guides →

Rats

For rats, dust is the whole conversation. Their respiratory tract is the weak point of the species.

Safe

Dust-extracted paper beddingThe default. Look for a stated dust-extraction process.
safe
HempLow dust, highly absorbent.
safe
Kiln-dried aspenSafe, and rats enjoy digging in it.
safe
Fleece hammocks and linersRats will use every soft surface you give them. Wash often.
safe

With a caveat

Cardboard beddingFine, but it needs frequent changing, and an ammonia smell means it is already overdue.
with a caveat

Never

Pine and cedar shavingsAromatic phenols destroy the cells lining the airway. In a species where respiratory disease is the leading cause of death, this is the worst possible choice.
never
SawdustDust plus softwood.
never
Scented litterFragrance is an irritant.
never

If you can smell ammonia at the cage, the rats have been breathing it for a while. That is a cleaning-frequency problem, not a bedding problem.

Read the rat care guides →

Gerbils

Gerbils tunnel. Substrate depth is not enrichment for them, it is the enclosure.

Safe

Deep paper and aspen mix, 20 cm or moreA gerbil needs a tunnel that holds its shape. Mixing paper with aspen and a little hay gives it structure.
safe
Plain chinchilla bathing sandEssential for coat condition.
safe
Hay woven through the substrateBinds the burrow walls.
safe

With a caveat

Coco fibreHolds a burrow well, but keep it dry — gerbils are desert animals.
with a caveat

Never

Pine and cedarAromatic phenols.
never
Shallow bedding in a tall cageA gerbil that cannot dig will bar-chew instead, and that is the standard sign of an inadequate setup.
never
Cotton-wool nesting materialEntanglement and ingestion risk.
never

Read the gerbil care guides →

Chinchillas

Chinchillas must stay dry. Their coat is dense enough that damp against the skin causes fungal problems.

Safe

Kiln-dried aspenAbsorbent and dry.
safe
Dust-extracted paper beddingWorks well; change promptly.
safe
Chinchilla bathing sand, offered for 10 to 15 minutes at a timeSand, not dust. Leaving the bath in permanently causes eye irritation.
safe

With a caveat

Fleece linersFine over absorbency, but a chinchilla on damp fleece is a fungal infection waiting to happen.
with a caveat

Never

Pine and cedarAromatic phenols.
never
Water bathsNever bathe a chinchilla in water. The coat does not dry through.
never

Read the chinchilla care guides →

Geckos

Match the substrate to the species' humidity, and never let a small gecko stand on anything it can swallow whole.

Safe

Topsoil and play sand mix for arid geckosPacks firm, holds a burrow, and is what a leopard gecko would actually stand on.
safe
Coco fibre and orchid bark for tropical geckosHolds the humidity a crested or day gecko needs.
safe
Paper towelCorrect for quarantine, for hatchlings, and for any animal whose output you are watching.
safe

With a caveat

Sphagnum mossExcellent in a humid hide, poor as a whole-floor substrate — it stays wet.
with a caveat

Never

Calcium sandSold as digestible, which is exactly why it gets eaten. Implicated in impaction.
never
Crushed walnut shellSharp and indigestible.
never
Loose play sand alone for hatchlingsToo easy to swallow at that size.
never

A humid hide is not optional for most geckos, whatever the main substrate is. Most stuck-shed problems trace back to its absence.

Read the gecko care guides →

Snakes

For snakes the substrate has to hold the right humidity for the shed, and let the animal get fully under it.

Safe

Cypress mulchHolds humidity without going sour quickly. A common default for tropical snakes.
safe
Aspen shavingsThe classic for colubrids. Excellent for burrowing; replace any patch that gets wet.
safe
Topsoil and coco fibre mixBioactive-ready and holds a burrow.
safe
Paper towel or newspaperQuarantine, feeding response problems, and post-surgery.
safe

With a caveat

Aspen in a high-humidity setupIt moulds. Aspen suits dry-side species; wet species need mulch or soil.
with a caveat

Never

Pine and cedarAromatic phenols.
never
Sand for species that are not desert animalsAbrasive and dries the skin, causing shed problems.
never

Stuck shed and retained eyecaps are usually a humidity failure during the blue phase, not a substrate failure afterwards.

Read the snake care guides →

Tortoises

Tortoise substrate has to hold a burrow and hold moisture, because dry-brooded tortoises pyramid.

Safe

Topsoil and coco coir mix, deep enough to dig intoHolds humidity at the shell without being wet at the surface.
safe
Orchid bark over soilCommon for humid-species tables.
safe

With a caveat

Sand and soil mixesFine for arid species, but keep the sand fraction low enough that it still packs.
with a caveat

Never

Pure sandEaten during grazing, and it does not hold a burrow.
never
Wood shavings of any softwoodPhenols, and they are eaten.
never
Rabbit pellets as a substrateSold for it. It moulds, and the tortoise eats a diet it was never meant to have.
never

Read the tortoise care guides →

Other Small Pets

Bedding has three jobs: absorb, stay dust-free, and let the animal dig. Anything aromatic is failing the second one.

This is the general small pets substrate list. It is what the tool answers with for Mice, Ferrets, Hedgehogs, Degus, Sugar Gliders and Opossums — every kind in this category without a table of its own.

Safe

Dust-extracted paper beddingThe default for almost every small mammal. Look for 'dust extracted' on the label rather than 'natural'.
safe
Kiln-dried aspen shavingsThe one wood that is fine, because it has no aromatic phenols. Kiln-dried matters.
safe
Hemp beddingVery absorbent and low dust. More expensive per litre but goes further.
safe
Soft meadow hay as a top layerFood and bedding at once for rabbits, guinea pigs and chinchillas. Never the only absorbent layer.
safe
Plain shredded paper or paper stripsUnprinted or soy-ink only. Cheap nesting material; poor as the main absorbent layer.
safe
Fleece liners over an absorbent layerOnly works with an absorbent layer underneath and a wash every few days. Fleece alone holds urine against the skin.
safe

With a caveat

Cardboard-based beddingFine, but it goes soggy quickly and needs changing more often than paper.
with a caveat
Sand bathsCorrect and important for chinchillas, degus and gerbils. Use plain chinchilla bathing sand, never 'dust' products and never builder's sand.
with a caveat
Hemp or straw pelletsGood absorbency, but too hard to burrow in. Use under a soft layer, not as the whole substrate.
with a caveat

Never

Pine and cedar shavingsThe aromatic phenols that make them smell pleasant are the problem: they damage the liver and kidneys and the cells lining the airway. Laboratory work found liver enzyme changes in mice after roughly a day of cedar exposure, taking well over a week away from it to settle, and enlarged livers in mice kept on pine for months.
never
Raw corncobTwo separate problems. It is swallowed and causes intestinal blockage, and it grows mould readily once damp.
never
Cotton wool and fluffy nesting materialSold as bedding, and it wraps around limbs and is swallowed. Repeatedly implicated in amputations in hamsters.
never
Scented or perfumed bedding of any kindAdded fragrance is an airway irritant in an animal whose nose is centimetres from the bedding all day.
never
Clumping cat litterSwallowed during grooming, and it clumps just as effectively inside the animal.
never
SawdustDust plus, usually, softwood. Both problems at once.
never

Depth matters as much as material for burrowing species. A hamster needs 25 cm or more of substrate it can actually tunnel through; shallow bedding on a large floor is still an inadequate enclosure.

Browse all Small Pets →

Other Reptiles

Substrate choice follows the animal's natural humidity, not the look of the vivarium. Get that pairing right and most substrate arguments disappear.

This is the general reptiles substrate list. It is what the tool answers with for Bearded Dragons, Skinks, Monitors, Turtles, Chameleons, Anoles, Uromastyx and Water Dragons — every kind in this category without a table of its own.

Safe

Topsoil and play sand mixThe standard bioactive-ready base for arid and semi-arid species. Plain topsoil with no fertiliser, no perlite, no wetting agents.
safe
Coco fibre and coirHolds humidity well for tropical species. Rinse and check it is not bone dry, which makes it dusty.
safe
Cypress mulchGood humidity retention for tropical snakes. Cypress specifically, not general 'wood mulch'.
safe
Orchid barkLong-lasting, holds humidity, resists compaction. Common in tropical vivaria.
safe
Paper towel or newspaperNot attractive, but correct for quarantine, for a new arrival, and for any animal being monitored for output.
safe
Leaf litter over a soil baseCover, humidity and invertebrate habitat in one. Sterilised, from a known source.
safe

With a caveat

Reptile carpetSnags claws and traps bacteria in the fibres. If used, it needs replacing rather than washing, often.
with a caveat
Sand alone for desert speciesReal desert is packed substrate, not loose play sand. Mix it with soil so it holds a burrow.
with a caveat
Bioactive setupsExcellent when established, but the clean-up crew needs weeks to establish before the animal goes in.
with a caveat

Never

Calcium sand and 'digestible' sandsMarketed as safe to eat, which encourages eating it. Implicated in impaction.
never
Crushed walnut shellSharp fragments, frequently implicated in impaction, with no advantage over soil.
never
Pine and cedarSame aromatic phenols as in rodent bedding, and the same airway damage.
never
Uncovered heat mats and unguarded ceramic emittersNot a substrate, but the most common cause of contact burns. Every heat source needs a thermostat, and every emitter needs a guard.
never

Impaction is far more often a temperature problem than a substrate problem: an animal that cannot reach its digestive temperature will not pass what it swallows, whatever it is standing on.

Browse all Reptiles →

Other Freshwater Fish

Substrate in an aquarium is a filter as much as a floor. Most of the biology lives in and on it.

This is the general freshwater fish substrate list. It is what the tool answers with for Bettas, Livebearers, Tetras, Danios & Minnows, Rasboras, Barbs, Catfish, Loaches, Goldfish, Cichlids, Gouramis, Shrimp, Pufferfish, Rainbowfish, Killifish and Snails — every kind in this category without a table of its own.

Safe

Inert aquarium gravelRinse thoroughly before use. Grain size should be too large to swallow and too small to trap food.
safe
Fine, smooth sandCorrect for corydoras, kuhli loaches and anything that sifts. Their barbels wear away on sharp gravel.
safe
Aquasoil for planted tanksExcellent for plants, but it leaches ammonia for the first weeks. Cycle around it; do not stock into it.
safe
Bare bottomLegitimate for quarantine and grow-out tanks. Easy to clean, but it holds far less biological filtration.
safe

With a caveat

Crushed coral or aragoniteDeliberately raises hardness and pH. Correct for rift-lake cichlids, wrong for soft-water species.
with a caveat
Very deep sand bedsAnaerobic pockets form below about 5 cm in still sand. Either keep it shallow or keep it stirred.
with a caveat
Painted or coated gravelUsually fine, but coatings chip. Test a handful in a jar for a week first.
with a caveat

Never

Sharp or angular gravel with bottom-dwellersWears down barbels and leads to infection in corydoras and loaches.
never
Anything containing metal, limestone of unknown origin, or shells in a soft-water tankSlowly alters chemistry in ways that are hard to diagnose later.
never

Browse all Freshwater Fish →

Other Saltwater Fish

In a marine system the rock and the sand are life support, and how you start them decides the first six months.

This is the general saltwater fish substrate list. It is what the tool answers with for Clownfish, Basslets, Gobies, Cardinalfish, Damselfish, Tangs, Dwarf Angelfish, Blennies, Wrasses, Dragonets, Dottybacks, Shrimp, Hawkfish, Rabbitfish and Snails — every kind in this category without a table of its own.

Safe

Aragonite sandThe standard marine substrate. Buffers pH and hosts the biology.
safe
Dry or cured live rockDry rock avoids importing pests but takes longer to mature. Cured rock is faster and riskier.
safe
Bare bottomCommon in high-flow systems. Easier to keep clean, but it removes a large part of the biological buffer.
safe

With a caveat

Deep sand bedsPowerful nutrient processing when they work and a sulphide release when they are disturbed. Choose shallow or deep deliberately, not by accident.
with a caveat
Uncured live rockIt will cycle the tank for you, and it will also bring in whatever was living in it.
with a caveat

Never

Silica play sandDoes not buffer, and it is commonly blamed for feeding diatom blooms in a new tank.
never
Any rock or decor of unknown originMetals and phosphate leach for months and are almost impossible to trace once the tank is running.
never

Browse all Saltwater Fish →

Keep going

158 care guides, same data

Every number these tools use comes from the species guides — read the one for your animal.

Browse the care guides →