Astrea Snail
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Specific Name: Astrea spp.
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Diet: Herbivore – grazes on diatoms, green film algae, and some cyanobacteria
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Pest or Good Guy: ✅ Good Guy
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Size: 2–4 cm
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Breed in Captivity: No – not known to reproduce successfully in reef tanks
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Cautions: Cannot right themselves if they fall; may die without assistance. Like most snails, sensitive to changes in salinity and copper.
Description:
Astrea snails are compact, hardworking algae grazers with a star-shaped base and pointed conical shell. They’re great for tight spots on live rock where larger snails can’t reach, and can help clear early film algae and even some cyano if it’s thin enough. However, they have a well-known weakness — if they fall onto their backs, they’re unlikely to flip over on their own and can die if not rescued. This makes them better suited to tanks where you can keep an eye on them, especially smaller nanos. Despite their clumsy moments, Astreas are reliable workhorses that can quickly clean up problem algae when added in the right numbers.