Astrea Snail – Detailed Guide: Care, Diet, and Breeding

Astrea Snail (Lithopoma tectum, Astraea tecta)

Astrea Snail is a common saltwater aquarium snail available these days. Sometimes hobbyists do not even have to buy them because they can accidentally make their way into tanks attached to live rocks or corals. In any case, these snails can be a great addition to community tanks. Why?

First of all, Astrea Snail care is relatively easy, making it a good snail for beginners. Second, these snails are well known for their hardiness and love for algae.

Below you will find all the information you need to know on how to care for Astrea snails, what to feed them and how to make a healthy snail home. Let’s get started.

Quick Notes about Astrea snail

Name Astrea snail
Other Names
Topshell snail, Trochus shell, Star snail, Conehead snail
Scientific Name Lithopoma tectum (Synonymised names: Astraea tecta, Trochus tectus)
Tank size (minimum) 5 gallons (~20 liters)
Keeping Easy
Breeding Medium   
Size (carapace) up to 6 cm (~2.4 inches)
Optimal Temperature 22 – 24°C  (~71°F – 75°F)
Water type SG = 1.021 – 1.026
Optimal PH 8.1 – 8.4
Optimal KH 7 – 12
Nitrate Less than 20 ppm
Diet Herbivorous
Temperament Peaceful
Life span up to 5 years
Color Form Reddish-orange to creamy-white coloration 

Taxonomy problem of Astrea snail

Astrea snail, commonly known as ‘Astraea tecta’, ‘Top shell’ or ‘Trochus shell’, is a member of the family Trochidae, a large family of marine gastropod molluscs containing several hundred species.

Here comes the problem nobody even mentions about. Even though the scientific name ‘Astraea tecta’ is routinely used in the trade,… it is wrong!

Astraea tecta name was not included in the WoRMs database. Instead of this, biologists use the synonyms ‘Trochus tectus’, now known as ‘Lithopoma tectum’.

Example of look-alike snail – Fenestrate Top Snail (Tectus fenestratus)

Regardless of the correct nomenclature of this species, it is clear that misidentification in the trade is a fundamental issue. In addition, it is very sad to see that lots (almost all) articles about Astrea snail repeat the same mistake. Obviously, nobody checks information anymore, it is just way easier to rewrite their care guides from other sources.

This kind of thing should not be in the pet trade. This is completely irresponsible!  Especially because there are look-alike species which are not that hardy compared to Astrea snail and may require a different set up with colder water. As a result, people might think that this species is not good enough for their aquariums, while in reality, it is not even an Astrea snail!

Natural Habitat of the Astrea snail

Astrea snails are distributed on outer reef flats and reef crests with abundant stony corals, on areas of turf algae for adults, and on intertidal reef flats with stony coral or rubble bottom for juveniles. They prefer higher energy environments where they can graze tough macroalgae and crustose coralline algae growing on hard substrates.

Typical colonies of Astrea snail occur in the shallows in the Caribbean Sea, the Gulf of Mexico, and the Lesser Antilles; in the Atlantic Ocean off Brazil. The optimum depth for these snails is between 1 m and 10 m, although they can be found as deep as 15 m.

Description of the Astrea snail

Astrea Snail (Lithopoma tectum, Astraea tecta)
Foto by Axel Alf

Astrea snails are relatively small snails. Their size ranges from 1 – 6 cm (0.4 – 2.4 inches) with an average of 2 – 4 cm (0.8 – 1.6 inches).

These snails have thick, elevated and broadly conical shell which has numerous very small conspicuous spikes protruding from it in a spiral form. These small projections on the shell give it a star-like outline.

The main color of the shells is reddish-orange, marked in places with white and olivaceous. The base of the shell is nearly flat. Astrea snails have a lid (trapdoor or operculum).
In captivity, Astrea snails usually live for about 3 to 5 years.

The Behavior of the Astrea snail

Astrea snails are non-aggressive, solitary, and docile by nature, liking a calm aquatic environment and peaceful tank mates. They do not have any means to attack other tank inhabitants and have only their operculum and shell for protection from aggressors.

Astrea snails are nocturnal. The pick of their activity starts at dusk and gradually stops during the night, before sunrise. Smaller snails display greater activity, reflected by more intense and longer movements. This nocturnal behavior is not uncommon for grazing gastropods and is mainly associated with attempting to avoid visual predators whilst feeding.

Interesting fact: On a 24-h cycle, dusk is a period in which algae had maximum nutrients at the end of the photosynthetic period corresponding to profitable conditions for grazers to feed at the end of the light period.

Astrea snails are not shy, they do not get scared easily. When placed on the bottom of the tank, they will soon crawl onto the corals and explore all the crevices in the tank.

When they grow into their adult size, their climbing ability gets worse. So, do not expect them to clean your side glasses. In addition, keep in mind that Astrea snail has difficulty righting itself if it falls or is knocked upside down. It is a pure miracle why they are not extinct yet, considering how often they end up upside down. So, it is advisable to check them from time to time.

They are not a burrower type of snails and remain active and spend the vast majority of their time below the waterline. Therefore, the risk of escaping is pretty low.

Are the Astrea snails Reef Safe?

Yes, they are reef safe. Astrea snails will not damage anything in a reef tank. When looking for food, they will not try to snack on corals. In addition, their small size prevents them from knocking over some freestanding corals that are on the bottom.

Feeding Astrea snail

Astrea snails are herbivorous and great scavengers. They feed by grazing on corals and rocks for microscopic algae as well as cyanobacteria and diatoms. They use strong and rasping radula to scrap the hair algae, brown algae, green algae, and filamentous algae from the rocks and boulders in a tank.

The only snails that outperform them are The Turbo snails. However, the small size of Astrea snails allows them to get to the holes and crevices which are unachievable for other members of the clean up crew.

In the aquarium, these snails will also feed on leftover shrimp or fish food, such as pills, flakes, pellets, algae/Spirulina wafers, frozen foods, etc.

Important: Astrea snails need a lot of food, so be prepared to supplement with herbivore pellets, (algae pellets, dried algae, etc.) if you do not have enough algae growth.

Be careful with copper: Astrea snails are sensitive to copper and copper compounds (read more here).

Like all snails, Astrea snails need calcium either in their diet or in the water (ideally, both) to make their shells hard enough to sustain their body. They have shells, which consist of calcium. Keeping calcium levels between 350 and 450 ppm is best.

I highly recommend reading my article “How to Supplement Shrimp and Snails with Calcium”.

You can read some of my related articles (the principle is the same with snails): How to Blanch Сucumbers and Zucchini for Shrimp.

Keeping Astrea snail

To put it in a nutshell, the true Astrea snails can survive, grow, and function even in sub-optimal water conditions. Their hardy nature makes them easy to care for, so both veterans and beginners can keep this species.

Nonetheless, we are not here to test their limits, so as with any aquarium inhabitant, you always need to make sure that the tank is set up correctly, and that the water is properly cycled. This ensures that you have the appropriate bacteria, which will convert harmful compounds into less harmful ones. 

Tank Size

These snails can live in the smallest marine tank. Therefore, depending on your livestock, the small tanks (5-gallon or 20-liter) can be good enough for a few Astrea snails.


Astrea snails do not need lighting. They are most active in the night. So, lighting should be adapted to the needs of fish, corals, sea anemones, etc.

Water Parameters

Although Astrea snails are extremely adaptable to a wide range of water parameters they still have some preferences.

They will thrive in the warm water. Therefore, the temperature should stay in the range of about 68 to 80 F (22 to 27 C) with around 71 to 75 (22 – 24C) being optimal. Therefore, it is advisable to install a heater and thermometer to control that the water is kept at a constant.

The pH should be kept around 8.1 to 8.4 and alkalinity should be kept in the range of 7 to 12 dKH, although these often go a little higher or lower.

Astrea snails need a specific gravity that is between 1.021 and 1.026.

Note:  Most care guides about Astrea snails say that they sensitive towards even small changes in water values. Well, once again it contradicts the real facts or maybe because these people have look-alike snails. For example, according to the experiment, Astrea snails survived without any losses reduced salinity by almost 50%. Low salinity was maintained in the treatment buckets for an additional 20 min followed by a rapid increase back to ambient levels. In addition, that kind of stress increased their hunger and they consumed more algae than non-stressed snails.

Nonetheless, I do not encourage this type of home experiments and would still recommend careful acclimation (read more about it here) as all invertebrates. Do it very slowly. In general, 2 – 3 hours will be good enough.

Basic Tank Equipment (links to check the price on Amazon)

Sexing Astrea snail

Astrea snails are gonochoric (separate male and female individuals), without any external sexual dimorphism.

Breeding Astrea snail

According to the observations, they reach reproductive maturity at 6 – 8 months old. Astrea snails are broadcast spawner, and fertilization takes place in the water column.

Spawning is initiated by males, and females spawn in response to the presence of seed in the water. Females generally spawn for 5–10 minutes, with individuals releasing more than 1 million oocytes (unfertilized eggs). The eggs are contaminated with transparent mucus, floating in the seawater.

Note: Do not worry, the water will clear soon enough. In a community tank, corals and other filter feeders will eat the particles that make the water cloudy. 

Spawning often occurs in synchrony with lunar or tidal cycles, generally occurring at night and within one or two nights of either a full or new moon. In nature, spawning occurs throughout the year in low latitudes and only during the warmer months in higher latitudes.

The developmental period is comparatively short and hatching occurs after the larvae reach the planktonic phase, approximately 12 – 24 hours after fertilization. After that, the larvae come out as free-swimming veligers. This stage lasts approximately 3 – 5 days and the veligers then settle onto the reef substrate and begin grazing on fine filamentous algae and microorganisms. In the ocean, the settlement may be delayed for about 10 days when the appropriate substrate is unavailable with the potential to drift outside the park boundaries.

Astrea snails larvae began to gradually metamorphose to the crawling stage at 6 to 8 days.

Although females can release more than 1 million eggs, the mortality rate is very high and only a few will survive and become adults.
Note: Unlike adults Astrea snails larvae cannot survive low salinities. In addition, fertilization, larval development, and larval metamorphosis is suppressed at salinities lower than 30‰.

Astrea snail and Suitable Tankmates

Most snails are known to be peaceful and solitary and Astrea snails are no exception. These snails will be good companions to dwarf shrimp and small, non-carnivorous fishes.

For example, they are compatible with:

Note: Adult Bumble Bee Snail can attack small Astrea snails if there is not enough food in the tank.

Under no circumstances keep Astrea snails with orange Claw Hermit Crab (Calcinus tibicen). In nature, 63.33% of the crabs preferentially occupy shells of Astraea tecta. The problem is that Hermit crabs can try to kill them just for their shells. Be very careful with other types of hermit crabs (like Halloween Hermit Crab, Blue Leg Hermit Crab) as well. Ideally, do not keep hermit crabs and Astrea snails together. Upside down snails are easy food for hermit crabs.

Coral banded shrimp and crabs can be a bit too dangerous for these snails as well. 

Buying and Checking Astrea Snail

Astrea Snail (Lithopoma tectum Astraea tecta) with pest snailsAstrea snails are not a rare saltwater snail species. On the contrary, it is possible to buy them almost everywhere. Most online aquarium stores sell them for as low as $ 1-5.
This snail species is a great addition to the tank in terms of aesthetics and also helps to keep the tank clean from waste and algae. However, sometimes they also require some cleaning.

Astrea snails can have their own pests in the form of teeny-tiny Pyramid snails. These parasites can even kill their host. Therefore, check your snails and remove any Pyramid snails the sooner the better.

In Conclusion

Astrea snails are excellent scavengers thereby helping to keep the tank algae and detritus free. They are hardy and are easy to care for snails. Therefore, they will be a good choice even for beginners. In general, Astrea snails are better adapted for a community tank than most.

What else can you expect from a small snail?

Foto by Jan Delsing

2 thoughts on “Astrea Snail – Detailed Guide: Care, Diet, and Breeding

  1. Michael wrote above, “Astrea snail has difficulty righting itself if it falls or is knocked upside down. It is a pure miracle why they are not extinct yet” . Having used Astrea Snails for over 25 years in many hundreds of reef aquariums as the best and most economical algae eaters, I disagree with that blanket statement. Initially, when purchased from store or online, all snails are practically starving to death. In that condition, of course they will be too weak to right themselves. Care should be taken by the hobbyist to set them upright if they fall, at least for the first 10 days. After that, provided they find enough algae, they can usually right themselves within a few minutes or overnight. When placing new snails in the tank, it’s best to set them in a pile in the corner, where algae on the glass has been left to grow for a week. Being in a pile near two panes of glass will ensure they can crawl over each other and onto the glass. Because they were starving, they will often travel just a few inches, eating, then rest for a day before moving further, gaining more strength every day.

    1. Hi Mark Peterson,
      Thank you for the feedback.
      Nonetheless, compared to other species, flipping over is not their strong side 🙂
      Best regards,

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