One of the most useful all-round cleanup snails in the reef hobby — a small, slender, pointed-shell gastropod (the trade's 'Florida cerith') that works both the sand bed and hard surfaces. It eats diatoms, film and hair algae, cyanobacteria and detritus on the substrate, rock and glass, and burrows through the top layer of sand to keep it stirred. Cheap, hardy and best bought in groups.
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Slender pointed shell to about 5 cm (2 in); most trade ceriths are smaller, around 1-3 cm.
Lifespan
1–3 years
Social needs
group
Native region
Western Atlantic and Caribbean (Florida to Brazil, Belize)
Origin
New World
Climate
⛅ Subtropical
Water type
🌊 Marine
Family
Cerithiidae
Genus
Cerithium
Part of the Marine Snails
Grazing and detritivore snails kept as reef-safe cleanup crew. Different species specialize in glass and rock algae, sand-bed detritus, or leftover food; stock to match available food, keep copper at zero, and acclimate slowly since snails are very sensitive to salinity shifts.
How this animal changes through its life — each stage often has its own care, diet and space needs.
Photo coming soon
Larva
Most marine invertebrates hatch into microscopic planktonic larvae (such as the zoea of crustaceans or the bipinnaria/veliger of echinoderms and mollusks) that drift and feed in the water column. The larva looks nothing like the adult and undergoes major reorganization.
Photo coming soon
Juvenile
After settling out of the plankton, the juvenile takes on a recognizable miniature of the adult body plan — a tiny shell, a small star, or a translucent shrimp. Crustaceans grow by molting, shedding the exoskeleton to enlarge.
Photo coming soon
Adult
Adults reach full size and reproductive maturity with the species' mature shell, shape, or coloration. Many continue to molt or grow throughout life, and some show sex differences in size or claw/appendage shape.
Color & pattern variants
Natural variants occur in the wild; selectively bred (man-made) variants were developed in captivity.
Natural
Florida Cerith (typical)
The standard trade form: a slender, tall-spired shell mottled in brown, grey and cream, sold as the 'Florida' or 'Atlantic' cerith. Color and exact size vary by individual and locality; not a bred strain.
Habitat & enclosure
Keep a group in any established reef or FOWLR tank of 10 gallons (38 L) or more with live rock and a sand bed to graze and sift. Maintain stable reef parameters: temperature 72-80F (22-27C), pH 8.1-8.4, salinity SG 1.024-1.026, alkalinity 8-11 dKH, calcium 400-450 ppm and low nitrate with zero ammonia/nitrite.
Cerithium atratum is a shallow western-Atlantic and Caribbean species, ranging from Florida south to Brazil and Belize on sand flats and reef rubble. Any reef lighting and gentle-to-moderate flow suit it; the key is having both sand to burrow in and algae-covered surfaces to graze.
Substrate
A sand bed of at least 1 inch (2.5 cm) is ideal so it can burrow and sift, alongside live rock and glass for grazing. It is one of the better snails for keeping the top layer of sand turned and free of diatom film; live sand best supplies the detritus it processes.
Equipment & setup
Standard marine equipment is enough: live-rock biofiltration, a heater, a protein skimmer for nutrient export and gentle-to-moderate flow. No special lighting is needed. Keep calcium and alkalinity stable to protect the shell.
Diet
A workhorse herbivore and detritivore: it grazes diatoms, film algae, hair algae, cyanobacteria and detritus off the sand, live rock and glass, and also processes organic matter in the top layer of the sand bed as it burrows. This dual sand-and-surface cleaning is why it is a clean-up-crew staple. In a very clean tank supplement with dried seaweed (nori) or sinking algae food so it does not starve.
Behavior & temperament
Peaceful and fully reef-safe toward fish, corals and other inverts. It is partly nocturnal, often burrowing into the sand by day and grazing rock and glass at night, so it can seem to 'disappear' before reappearing. Harmless and non-reproductive enough to overrun a tank in most cases. Stock several at once, since a single small snail makes little dent in algae and they naturally occur in numbers.
Health
Like all marine snails it is extremely sensitive to copper, so copper-based medications are off-limits, and to salinity and temperature swings, so drip-acclimate slowly over 1-2 hours and never lift it into the air. Soft, eroding shell tips signal low calcium/alkalinity or acidic water; keep these stable. The main practical killers are starvation in spotless tanks and being eaten by hermit crabs for the shell, so supply spare shells if hermits are present, and remove any dead snail promptly as decaying tissue fouls water fast. (Educational only, not a substitute for advice from an aquatic veterinarian.)
Tips, DIY & hacks
Buy ceriths in groups, not singly, and stock to your algae and sand area rather than water volume. Drip-acclimate slowly and never expose them to air. If you keep hermit crabs, provide spare empty shells so they don't kill the ceriths for their shells. Great choice for diatom-dusted sand and film-algae control.
Reviewed and signed off by: KinStation Editorial — pre-launch draft (pending DVM review) on 2026-06-10