Nassarius Snail (Nassarius vibex): Care, Diet and Tank Size

The sand looks empty. Then a pellet sinks, and within a minute a dozen thin siphons pop up out of the bed, followed by small shells racing toward the food. That is a nassarius crew, and it is half the reason people keep them.

The nassarius snail sold in the trade as Nassarius vibex, the bruised nassa, is a small scavenging snail from the western Atlantic, ranging from Cape Cod through Florida and the Gulf to the West Indies. Some references now place it in the genus Phrontis. It is part of our Florida Keys clean up crew field guide.

Quick facts

What a nassarius snail eats

Nassarius are scavengers. The Animal Diversity Web account describes N. vibex as feeding mainly on carrion, coming out of the sand and moving up-current toward food. The Bailey-Matthews Shell Museum calls them voracious scavengers that can find a carcass from a long way off. In a tank that means leftover food, a dead snail or a fish that died out of sight. They get to it before it rots under the sand.

They do not eat algae. If you want glass and rock cleaned, that is astrea and trochus work. Nassarius keep the sand from hiding food that would otherwise break down into nitrate and phosphate.

The sand bed

A nassarius spends most of its life buried, with only its siphon above the sand to sense food. It needs an actual sand bed, an inch or more of fine to medium sand, to do that. In a bare-bottom tank it has nowhere to hide, and it is not much use.

How many nassarius snails per gallon

Our clean up crew calculator does not add nassarius on its own, so use the same light-start rule it uses for the rest of the sand crew. Start near one per 10 gallons of sand bed in an established tank: four in a 40, seven or eight in a 75. Top Shelf Aquatics publishes similar tiers, about 4 to 6 for a 40 to 55 gallon tank and 6 to 10 for 75 to 120 gallons.

A nassarius crew only eats what reaches the sand. If you feed lightly, or the tank has a fighting conch, ceriths and hermits already working the bed, err low. A snail that sits on top of the sand all day instead of burying is often a hungry one.

Acclimation

Float the sealed bag for about 15 minutes to match temperature. Then drip tank water in slowly to match salinity, because invertebrates are sensitive to salinity swings. Never add the shipping water to your tank. Drop the snails on open sand and they will bury on their own.

Copper is toxic to snails. Never add one to a tank that has had copper in it.

Lifespan and size

The Shell Museum gives a shell length of a bit over half an inch. Animal Diversity Web notes that researchers have found the species can live for several years, without giving an exact figure.

How we find them in the Florida Keys

In the wild, N. vibex lives buried in shallow sand and mud flats, in very shallow water and along creek banks. It comes up when the tide brings the scent of food. We collect them by hand under our Florida certificate and condition them in our Key West systems before they ship.

Common problems and how to avoid them

• Hermit crabs. A hungry hermit will take a small snail. Keep spare shells and feed the tank.
• Snails sitting on top of the sand. Usually hunger, sometimes poor water. Feed a little and test salinity and ammonia.
• Snails climbing out of the water. Often a sign of a water quality problem. Test before anything else.
• Too many snails in a lightly fed tank. They starve quietly under the sand. Start light.

FAQ

The Underwater Gardener is a reef store in Key West, Florida. Our Florida Keys clean up crew is collected by our team under Florida certificate #AQ0254072 and conditioned in our Key West systems before it ships. Livestock ships UPS Next Day Air on Tuesdays and Wednesdays.