Cerith Snail

Cerith Snails (Cerithium sp.) do their best work while you're asleep — nocturnal by nature, they spend the night moving methodically through the sand bed and over rockwork, breaking down detritus and consuming diatoms, cyanobacteria, and decaying organic matter before it enters the nitrogen cycle as a nitrate precursor. By day they mostly stay buried in the sand or tucked into rockwork, so they contribute more to tank health than their daytime invisibility suggests.

They're one of the more genuinely useful sand bed cleaners in a reef cleanup crew because they work the interface between sand surface and water column where a lot of organics accumulate — the zone that nassarius snails go deeper than and hermit crabs stay above. That ecological niche specificity means a mixed cleanup crew with cerith snails, nassarius snails, and hermit crabs covers the full range of sand bed maintenance more completely than any single species alone.

They don't need target feeding in an established reef — the natural organic load in a typical reef tank is more than sufficient. In a bare or newly established system, occasional small amounts of sinking food placed at night help sustain them while the biological load builds up.

Scientific name: Cerithium sp. (several species sold as "cerith snail" in the trade)
Origin: Tropical Indo-Pacific and Caribbean — sandy reef zones, seagrass beds, and intertidal sand flats
Water parameters: Temp 72–80°F · Salinity 1.023–1.026 · pH 8.1–8.4
Tank requirements: 10 gal minimum; live sand substrate recommended
Diet: Herbivore/detritivore — algae, diatoms, cyanobacteria, detritus, and decaying organic matter
Compatibility: Reef safe; peaceful with all species; hermit crabs may target them for their shells
Husbandry note: Stock cerith snails at roughly 1–2 per 5 gallons of tank volume as a starting point. Overstocking any single cleanup crew species creates competition for food that leads to die-offs — a diverse crew at moderate density outperforms a large single-species crew.