From ReefPedia

[edit] Nassarius Snail Scientific Name Nassaurius vibex Max. Size: Shell size as big around as a quarter is the largest I have seen. Their foot trails behind about a full shell length as they travel. Tank Size: Anything from a five gallon nano tank to a 1,000 gallon aquarium. One per 2 gallons is a good rule of thumb as far as tank population/distribution. Aggression: Not aggressive toward any reef inhabitants, but when it comes to detritus or uneaten foods they are tremendous and relentless scavengers. Hardiness: Very hardy as long as they are not exposed to high nitrate levels. Reef-Safe: Absolutely reef safe for all tanks with a 4" deep sand bed. A must in my opinion, as the ultimate sand stirrer. Available as captive-bred: The Nassarius Snail is extremely difficult to breed in captivity. Hitchhiker? N/A

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Physical Description

The Nassarius snail is a small scavenger with an oval spiral shell that resembles an olive pit, with a long tube like siphon that protrudes from the end of the shell. One of the most ideal scavengers and detritus eaters these snails are perfect for the reef aquarium, quickly consuming detritus, uneaten food, decaying organics, and fish waste. Nassarius snails like to bury themselves in the sand, which will help maintain adequate oxygen levels in the substrate.

Distribution

Predominantly obtained from the Atlantic/Caribbean.

Taxonomic Stuff you know you Care About

• Family: Nassariidae

• Genus: Nassaurius

• Species: vibex

Behavior

Nassarius snails will spend the majority of their time on subteranean patrol beneath the surface of the sand bed. They literally plow the sand providing excellent aeration while cleaning the sand by eating the detritous that accumulates. If turned over on their back, these snails can quickly flip themselves upright.

When you feed the tank, they sense the food with their proboscus/siphon tube and come bubbling out of the sand in search of stray meaty or flake foods. After they are finished they quickly bury themselves leaving furros of sand and a small mound of sand as a reminder they were top side.

Watching them in action is nothing short of amazing. If a Nassarius senses food in the water it will come swarming out of the sand where it might be buried, then stop and point its nose in various directions till it finally senses where the delicious aroma is coming from. It will then travel faster than any snail you have seen to onto the carrion. A "search pattern" can be instituted, where a Nassarius that knows food is out there but cannot sense its location with its nose will travel a certain direction for a short while then turn around and come back past where it started from. Amazing creature!

Feeding

No direct feeding required as they are detrivores/scavengers.

Breeding

Will lay eggs in the aquarium, but chances of propagation are very minimal.

Social Structure

As with most snails they are independent travelers, but I have seen a dozen converge/swarm on the carcass of a dead fish and leave nothing but the bones. They munch very peaceably together before returning to the sand bed.

Additional Notes

Many snails are sold as Nassarius that really aren't. For example, see Mike Greenemeier's article: Do You Know Who You're Dealing With? Get to Know the Real Ilyanassa obsoleta