Knowledge Centre · Starting a new aquarium
Choosing an aquarium substrate: sand, gravel or bare-bottom?
Substrate choice looks cosmetic from a shop shelf, but it's really a decision about who and what you're keeping. Sand is the safer default for barbelled bottom-dwellers and most burrowing species; gravel is easier to source and vacuum but carries a documented welfare risk for those same fish; bare-bottom trades every aesthetic benefit for maximum cleanability; and a planted tank has its own substrate priorities entirely separate from either. This guide compares the options against what actually determines the right answer — your stocking plan — rather than appearance alone.
Before you choose
This guide helps if…
You already know roughly what you're planning to stock — corydoras, kuhli loaches, shrimp, a planted layout, or a general community — and want to match substrate to that plan rather than picking on looks alone.
Look elsewhere first if…
You haven't yet decided on livestock or a planted vs unplanted layout — our best beginner fish and starting a planted aquarium guides are a better starting point, since stocking should generally drive substrate choice, not the other way round.
Worth knowing: substrate is one of the more expensive things to change your mind about after the tank is stocked and decorated. Deciding based on your actual livestock plan up front avoids a full teardown later.
Sand
Fine, smooth-grained sand is the widely recommended substrate for barbelled and burrowing species, since it doesn't abrade the sensitive sensory tissue those fish rely on to find food[1]. It also suits burrowing behaviour more naturally than gravel, and many keepers prefer its appearance for a naturalistic aquascape. The trade-off: sand can compact more than gravel if never disturbed, sometimes trapping pockets of gas beneath the surface, and it's less forgiving of a standard gravel vacuum's suction, which will pull sand up with the debris if used carelessly.
Gravel
Gravel is widely available, straightforward to vacuum with a standard aquarium siphon, and doesn't compact the way sand can. For a general community tank without barbelled bottom-dwellers, it's a perfectly reasonable, low-maintenance default. The genuine limitation is species-specific rather than general: coarse or sharp gravel is commonly linked to barbel abrasion in corydoras, kuhli loaches and similar fish, and once that sensory tissue is eroded, it's widely reported not to reliably regrow to its original length[1]. If you're not keeping species with this specific sensitivity, gravel's practical advantages are real; if you are, sand is the safer choice, covered further below.
Bare-bottom
No substrate at all is a deliberate, common choice for shrimp-breeding tanks, quarantine and hospital tanks, and some dedicated grow-out setups, precisely because it maximises cleanability — waste is visible and easy to remove, and there's no substrate to trap it. It offers bottom-dwelling species nothing to forage or dig in, provides no plant-rooting medium, and most keepers find the stark look unsuited to a display tank meant to be looked at rather than just maintained. It's a legitimate, purpose-driven choice for a specific tank's job, not a general-purpose default.
Planted substrate and aqua soil
A planted tank has its own substrate priority: root access to nutrients. A nutrient-rich aqua soil, or plain sand or gravel supplemented with root tabs, makes growing anything beyond a handful of low-demand, water-column-feeding plants considerably easier than an unsupplemented substrate. This is a genuinely separate decision axis from the barbelled-species question above — a fine, nutrient-capped sand can serve both a planted layout and a corydoras-safe substrate at once, while a coarse aqua soil marketed for planted tanks isn't automatically barbel-safe just because it's plant-friendly. Check both needs against your actual stocking plan rather than assuming one substrate choice automatically satisfies the other. See our starting a planted aquarium guide for fertilising and substrate depth in full.
Barbelled and burrowing species
This is the clearest, most welfare-relevant substrate decision on this page, and it's worth naming directly rather than folding into the general sand-vs-gravel comparison above. Corydoras use their barbels constantly while foraging, and our corydoras catfish guide covers barbel erosion as a genuine, largely irreversible welfare issue linked to coarse or sharp substrate[1]. Kuhli loaches are burrowers as well as barbel-users, and our kuhli loach guide covers the same substrate sensitivity in detail, including a dedicated common-mistake entry for exactly this[2]. If either species, or a similar barbelled or burrowing fish, is part of your stocking plan, fine sand isn't a nice-to-have — treat it as close to a requirement.
Shrimp and pH-sensitive invertebrates
Shrimp don't have the barbel-abrasion risk fish do, but substrate choice still matters for them: some substrates marketed for shrimp or planted tanks are formulated to buffer pH downward, which can suit soft-water species but is a genuine problem if you're not expecting or monitoring that shift. Check any substrate's stated chemistry effects before adding it to a shrimp tank, and confirm your actual water parameters afterwards with our pH and water hardness guides rather than assuming a "shrimp-safe" label means chemically inert.
Comparison at a glance
| Substrate | Best suited to | Barbelled/burrowing safety | Cleaning |
|---|---|---|---|
| Fine sand | Corydoras, kuhli loaches, burrowing species, naturalistic aquascapes | Widely recommended as the safer choice | Needs a gentler vacuum technique; can compact if undisturbed |
| Gravel | General community tanks without barbelled bottom-dwellers | Coarse or sharp gravel is a documented risk | Straightforward with a standard siphon |
| Bare-bottom | Shrimp breeding, quarantine, hospital tanks | No abrasion risk, but no foraging medium either | Easiest to keep visibly clean |
| Aqua soil / planted substrate | Demanding planted layouts | Depends on grain size — check before assuming barbel-safe | Not typically deep-vacuumed once planted |
Common mistakes
- Choosing gravel for a tank that will house corydoras or kuhli loaches, without knowing about the barbel-abrasion risk until after the fish are already showing signs.
- Assuming a "planted tank" aqua soil is automatically barbel-safe because it's marketed for plants, rather than checking its actual grain size and sharpness.
- Vacuuming sand with the same technique used for gravel, pulling large amounts of substrate up with the debris.
- Adding a pH-buffering substrate to a shrimp tank without expecting or monitoring the shift it causes.
- Changing substrate type after a tank is already stocked and decorated, turning a planning decision into a full teardown.
Frequently asked questions
Is sand or gravel better for a beginner aquarium?
Neither is universally better — gravel is generally more forgiving to vacuum and keep clean for a first-time keeper, while fine sand suits a wider range of species safely and looks different aesthetically. If you're not yet planning to keep barbelled bottom-dwellers or burrowing species, either is a reasonable beginner choice; check the rest of this guide against your actual stocking plan before deciding.
Can I keep corydoras or kuhli loaches on gravel?
It's widely reported as a genuine welfare risk. Both groups use sensitive barbels to feel for food along the substrate, and coarse or sharp gravel is commonly linked to barbel erosion that doesn't reliably regrow to its original length. Fine, smooth sand is the widely recommended substrate for both — see our corydoras and kuhli loach guides for the full detail.
Do I need special substrate for a planted tank?
Not strictly, but a nutrient-rich aqua soil or root-tab-supplemented substrate makes growing anything beyond low-demand plants considerably easier, since it feeds roots directly rather than relying entirely on water-column fertilisation. Plain sand or gravel can still support a planted tank with the right supplemental fertilising routine — see our starting a planted aquarium guide for the full picture.
Is bare-bottom the easiest option to maintain?
In terms of cleaning, generally yes — there's no substrate to vacuum and waste is easy to see and remove. It's a common deliberate choice for shrimp-breeding, quarantine and hospital tanks for exactly that reason. The trade-off is that it looks starkly utilitarian to most keepers, offers bottom-dwelling species no natural substrate to forage or burrow in, and provides no rooting medium for plants.
How AquaPulse can help
Some substrates, particularly those formulated for planted or shrimp tanks, shift pH or hardness for weeks after setup before settling. Noticing that settling process, rather than mistaking it for instability or a separate problem, depends on comparing today's reading against a genuine record of the last few weeks, not a general impression of "it's been fine so far."
AquaPulse works from the readings and context you enter — it doesn't measure your water automatically. Logging pH and hardness after a substrate change in AquaPulse keeps that settling pattern visible, so you can tell a substrate finding its equilibrium apart from a genuine ongoing issue. Get AquaPulse on the App Store or Google Play to try it, or see the Water Check feature page for more detail.
Sources and editorial information
- Published
- 8 August 2026
- Last reviewed
- 8 August 2026
- Written and maintained by
- AquaPulse (Valeon Labs Ltd)
This guide synthesises the barbel-safety research already published and cited in our own corydoras catfish and kuhli loach guides, rather than introducing new external research — see those guides' own sources sections for the underlying citations. The remaining comparisons (gravel, bare-bottom, planted substrate) reflect widely shared, largely uncontroversial hobby practice rather than a single study, and we've said so explicitly rather than presenting a comparative judgement as settled science. We'll update this page if we find something we've got wrong.
Good to know: This guide provides general informational guidance only, to help with a planning decision, not a recommendation of a specific brand or product.
- [1] AquaPulse — "Corydoras catfish care" Our own already-published, separately sourced guide. Used directly for the barbel-erosion welfare risk from coarse or sharp substrate rather than re-deriving the same research here.
- [2] AquaPulse — "Kuhli loach care" Our own already-published, separately sourced guide. Used directly for the same substrate-sensitivity content as it applies to kuhli loaches specifically.
What we deliberately left out: specific commercial product or brand recommendations, since suitable options and formulations change over time and vary by region; and a precise numeric grain-size threshold separating "safe" from "unsafe" sand or gravel, since we couldn't find a single consistent figure across sources and didn't want to imply false precision where the underlying guidance is closer to "smooth and fine" than any measured cutoff.