equipment

Sand vs gravel

Which substrate should go in the tank?

Short answer

For corydoras, kuhli loaches, dwarf cichlids and any barbelled bottom-dweller, sand is a welfare requirement rather than a preference. For everything else it is largely an aesthetic and maintenance decision.

Side by side

Dimension	Sand	Gravel	Favours
Suits sifting and burrowing species	Yes	No — sharp gravel erodes barbels	Sand
Waste visibility	Sits on the surface, easy to siphon	Falls between grains	Sand
Vacuuming	Hover above the surface	Push into the bed	Neither
Anaerobic pockets	Possible in deep undisturbed beds	Rare	Gravel
Plant rooting	Good, with root tabs	Good, with root tabs	Neither
Gets into filters	Yes, if fine and stirred up	No	Gravel
Appearance	Natural for most habitats	Varies	—

Which to choose

Sand

Choose sand if the tank contains any barbelled bottom-dweller, any sand-sifter, or any Tanganyikan shell-dweller.

Gravel

Choose gravel for a tank with no bottom-dwelling species that needs sand, or where you want minimal maintenance fuss.

One caveat

Malaysian trumpet snails turn over a deep sand bed continuously and largely eliminate the anaerobic-pocket concern — which is the main argument against sand.