Why do my Astrea snails keep dying when they fall off the glass?

Astrea snails originate from rocky environments where they can reach out and grab a nearby ledge if they tumble. On a flat aquarium sandbed, they often cannot reach anything to right themselves. If left upside down, they become stressed, vulnerable to predators like hermit crabs, and will eventually starve. You must manually flip them over.

How many Astrea snails should I put in my tank?

A general rule is one snail per 15 to 20 litres, but this depends entirely on the amount of algae in your tank. It is better to start with fewer snails and add more if needed, rather than overstocking and having them starve.

Will Astrea snails eat my corals?

No, Astrea snails are strictly herbivorous. They are completely reef safe and will only graze on the algae growing around the base of your corals, leaving the coral tissue unharmed.

Why is my new Astrea snail not moving?

Snails can remain stationary for a day or two as they adjust to new water chemistry. However, if they were not drip-acclimatised properly, they may be suffering from osmotic shock. Check that the snail does not smell foul (a sign it has died) and ensure your water parameters are stable.

MarineMarineBeginner

Astrea Snail

Lithopoma spp.

A highly effective and peaceful herbivore, the Astrea snail is a staple of the marine clean-up crew, renowned for clearing diatoms and film algae.

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Ideal Conditions

Temperature: 22 – 26 °C
pH range: 8.1 – 8.4
Salinity: 1.023 – 1.025 SG
Adult size: 2.5 – 4 cm
Nano reef or larger: 30 litres+
Lifespan: 1 – 3 years
Diet: Herbivore
Water flow: Moderate
Preferred setup: Ample rockwork for grazing; established tank with algae growth.

About the Astrea Snail

The Astrea snail (historically traded under the genus Astraea but scientifically reclassified as Lithopoma) is one of the most popular clean-up crew invertebrates in the marine aquarium hobby. Characterised by their distinctive, pyramidal shells that often become encrusted with beautiful purple or pink coralline algae, these snails are relentless workers. They spend the vast majority of their time grazing on rockwork and glass, making them invaluable for controlling nuisance algae in reef aquariums.

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Is it right for your tank?

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Where Astrea Snail comes from

Native range

Caribbean Sea, Gulf of Mexico, Western Atlantic

Countries / regions

United States, Mexico, Bahamas

Habitat

Rocky reefs, intertidal zones, and areas with heavy rubble where algae growth is abundant.

Most specimens in the aquarium trade are collected from the coastal waters of Florida and the Caribbean.

Similar species

Trochus Snail
Trochus spp.
Turbo Snail
Turbo fluctuosus
Cerith Snail
Cerithium spp.

We’re adding more full species guides as the catalogue grows.

Compatible tank mates

Reviewed guidance based on this species' recorded traits.

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Ocellaris Clownfish
Amphiprion ocellaris
Peaceful fish that will completely ignore the snails.
Great
Emerald Crab
Mithraculus sculptus
An excellent companion in a reef clean-up crew; they rarely compete directly and ignore each other.
Great
Blue-legged Hermit Crab
Clibanarius tricolor
Hermit crabs are opportunistic and may kill Astrea snails to steal their shells if empty shells are not provided.
Compatible with caution
Picasso Triggerfish
Rhinecanthus aculeatus
Triggerfish have strong jaws designed to crush and eat molluscs and invertebrates.
Not recommended
Dogface Puffer
Arothron nigropunctatus
Pufferfish are specialised predators of hard-shelled invertebrates and will rapidly consume the snails.
Not recommended

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