Astraea Snails

Astraea Snails have an incredible hunger for algae but are practically helpless when flipped over and may need your help.

Despite that, they’re one of my favorite types of snails because they’re readily available for a few bucks a piece and do well once established.

Read this guide to learn how to support these hardworking snails and maximize their cleaning potential in your tank.

What Astraea Snails Look Like

Astraea snails have conical shells with spiral ridges and a rough, bumpy texture. Their shells range from light tan to dark brown, sometimes reddish or greenish hues from algae growth such as Coraline.

Flip one over, and you’ll spot a round, flat base with a pearly, iridescent operculum that serves as their trap door. They also have two small eyestalks and a pair of sensory tentacles, always on the lookout for their next meal.

You might confuse them with:

• Trochus snails: While very similar, the best way to tell the difference is that its operculum is darker. They often have a more pronounced conical shape, are more active climbers on aquarium glass, and can right themselves if flipped over.
• Tectus snails (Star snail): Similar to Astraea, they often have a more distinct, star-like pattern or checkerboard appearance on the shell surface and can be more pointed at the apex. They are often better at righting themselves if flipped over and tend to be more tolerant of varied tank conditions.

Turban snails & Turbo snails: “Turban Snail” is commonly used for snails in the Turbinidae family, including Astraea, Turbo, and others. However, they are more known as being Turbo snails. Astraea typically has more pronounced ridges and a conical appearance than the smoother, more rounded Turbo varieties.

Diet And Feeding

Astraea snails have a voracious appetite for various types of algae, making them helpful additions to your clean-up crew.

Their diet primarily consists of:

• Filamentous algae (hair algae, turf algae)
• Diatoms and other microalgae
• Soft film algae on rocks, glass, and Coraline algae (not the Coraline itself)
• Cyanobacteria (blue-green algae)

Unfortunately, they don’t seem to have a taste for Bryopsis, which is a plague algae that can destroy systems.

You’ll often spot these snails working their way across rocks and tank walls, leaving visible “grazing trails” in their wake.

While they do their best work at night, I still find them somewhat active with the lights on.

While they prefer natural algae growth, I’ve found that in newer tanks or during lean times, you can add dried seaweed or algae-based foods to their diet. Just don’t expect them to show much interest in prepared foods – they’re all about the real deal.

Astraea snails don’t pose any risk to corals or other tank inhabitants. They’re strictly herbivores, focusing solely on algae.

Tank Setup And Acclimation

Astraea snails thrive in a well-established reef tank with a lot of live rock and a sandy substrate. They’re not picky about lighting, but moderate to high lighting promotes algae growth for grazing.

Low to moderate water flow is ideal so as not to impede their movement. It might be a flow issue if you notice them only sticking to one area of your tank, even when food of plenty in another.

I always match bag water temperature and salinity as much as possible before placing them in my main display. The only concern I usually have is if any hitchhikers on their shells need to be removed. The worst offender I’ve come across is Bryopsis. It’s best to leave those that are infected at the store.

Astraeas are sensitive to any form of dips or treatments, so they’re best avoided. Anything with copper or high nitrates is lethal to them.

How many Astraea snails can you keep in a reef tank? I think one snail per 5-10 gallons, depending on your algae levels and the space available for them to roam without getting stuck. In a 30-gallon tank, I’d start with 3-4 snails and monitor for a month or two.

Behavior And Tank Mates

During the day, you might find them nestled in crevices or motionless on vertical surfaces, but as the lights dim, they should spring into action, methodically scaling tank walls and equipment. These solitary creatures don’t school or coordinate, but they tolerate their own kind just fine.

Suitable tank mates:

• Most reef-safe fish (clownfish, gobies, tangs)
• Peaceful invertebrates (some hermit crabs, cleaner shrimp)
• Corals of all types

Species to avoid:

• Pufferfish and triggerfish (snail predators)
• Large, aggressive wrasses
• Mantis shrimp and some large crabs or hermits that don’t have empty shells available

Can Astraea snails survive if they fall upside down? Yes, but they may need assistance. If you notice an Astraea upside down for more than a few hours, gently flip it over to prevent stress and potential starvation. Trochus snails are much more appealing to me as they can flip over themselves.

Breeding And Reproduction

You might occasionally see what appears to be spawning behavior – snails clustering together and releasing white cloudy plumes into the water.

This can cause temporary cloudiness in your tank, but it’s harmless and typically clears up with good filtration. Some corals might enjoy the extra nutrients that it provides.

Don’t count on breeding to maintain your Astraea population. You’ll still need to spend a few bucks for new additions to keep the population stable in your reef.

Even if eggs are released, the planktonic larval stage is nearly impossible to support in a home reef tank. The few reported successes I’ve come across usually result in minimal survival rates, with only a handful of juveniles making it to adulthood.

If you do spot tiny snails in your tank months after a spawning event, consider yourself lucky!

Astraea Snails Tips

Keeping your Astraea snails healthy is all about shell maintenance and stable water conditions.

Watch for signs of shell erosion like pitting or thinning, especially near the aperture. If you spot this, check your alkalinity and calcium levels.

“Falling syndrome” is another red flag if your snails constantly detach from surfaces. It’s often a sign of stress or poor nutrition.

Remember, these guys are copper-sensitive, so avoid any treatments containing this metal. Regular water testing and stable parameters are your best bet for long-term snail health.

Can You Keep Astraea Snails In A Reef Jar?

I’ve experimented with Astraea snails in a pico setup, and I don’t think it’s ideal.

• Limited surface area for grazing can lead to nutritional deficiencies
• Water changes in a reef jar cause a lot of stress on them
• Accidental falls from jar walls or rocks will likely lead to death, contaminating your whole setup

If you’re dead set on adding an Astraea to your reef jar, limit it to one snail max. You’ll need to be vigilant about water quality, and you may need to supplement their diet as mentioned before.

Personally, I’d recommend sticking to even smaller snails like a Stomatella snail for pico reefs. They’re better suited to the limited resources and potential instability of these tiny ecosystems.

Just because you can keep an animal in a certain setup doesn’t always mean you should. In my experience, Astraea snails thrive in larger, more stable reef environments with room to roam and plenty of surfaces to graze.