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Nassa mud snail

Nassarius obvelatus

A classic zombie snail that lives beneath the sand, rising like a submarine when food enters the water. A critical detritivore, it requires a soft sand bed to bury itself and aerate the substrate.

Taxonomy

Class:Gastropoda

Order:Neogastropoda

Family:Nassariidae

Subfamily:Nassariinae

Genus:Nassarius

Species:Nassarius obvelatus

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Water Temperature

22 - 28 °C

pH Value

8.1 - 8.4

Water type

Marine

Invertebrate type

Freshwater snail

Adult size

1.8 cm

Minimum group

>= 1

8 - 12 dKH

Ecological role

Herbivore

Species description

Geographical Origin and Habitat: Widely distributed in the tropical waters of the Indo-Pacific, from East Africa and the Red Sea to northern Australia, the Philippines, and French Polynesia. It inhabits shallow coastal waters, sandy lagoons, seagrass beds, and intertidal mud flats at depths of 0 to 15 meters.

Taxonomy: Nassarius obvelatus is a gastropod mollusk belonging to the family Nassariidae, genus Nassarius. Commonly known as the Nassa mud snail or dog whelk. It is characterized by a long, flexible siphon used to detect chemical scent trails of decaying organic matter in the water.

Social Behavior: A peaceful, harmless scavenger that spends most of its time buried beneath the sand bed. It performs a vital ecosystem service by aerating the substrate and preventing the buildup of anaerobic toxic zones. When food is introduced, they emerge rapidly from the sand like tiny submarines.

Coloration and Sexual Dimorphism: Features a robust, ribbed, oval-conical shell. Shell colors range from grayish-white to light beige or tan, occasionally marked with darker brown spiral bands. There is no visible external sexual dimorphism; males and females are morphologically identical.

Care, breeding and tankmates

Tank Setup: Suitable for nano reefs and larger aquariums starting from 30-50 liters (10-15 gallons). The primary requirement is a soft sand bed of at least 4-6 cm in depth, allowing the snail to bury itself completely. Coarse or rocky substrates should be avoided as they prevent burrowing.

Diet and Feeding: Strictly a detritivore and scavenger. It does not consume healthy algae but eagerly feeds on leftover fish food (frozen, flakes, pellets), organic waste, and dead animal matter. It is a critical component of the aquarium's clean-up crew to prevent ammonia spikes.

Water Quality: Requires standard, stable marine parameters: salinity/specific gravity of 1.023-1.025, temperature of 22-27°C (72-81°F), pH of 8.1-8.4, and dKH of 8-12. As with all invertebrates, it is highly sensitive to copper treatments. Calcium levels should be monitored for shell strength.

Compatibility and Tankmates: Exceptionally reef-safe. Compatible with peaceful community fish, corals, and other non-predatory invertebrates. Avoid housing with snail-eating predators such as triggerfish, puffers, large wrasses, or aggressive hermit crabs.

Aquarium Breeding: Spawning can occur in home aquariums, with females laying small, capsule-like eggs in transparent sheets on the glass or rocks. However, the planktonic larvae are usually removed by filtration or eaten by corals, so they rarely reach adulthood in a standard setup.

Risks and Diseases: The main risk is starvation in sterile tanks with no fish population or very low feeding rates. They are highly sensitive to osmotic shock, so slow drip acclimation is necessary when introducing them to a new aquarium.

Geographic Origin and Distribution

Widely distributed in the tropical waters of the Indo-Pacific, from East Africa and the Red Sea to northern Australia, the Philippines, and French Polynesia. It inhabits shallow coastal waters, sandy lagoons, seagrass beds, and intertidal mud flats at depths of 0 to 15 meters.

Origin

Tropical oceans and reefsAfrica and MadagascarSouth and Southeast AsiaAustralia, New Guinea, and Oceania

Invertebrate profile

Diet: Carnivore
Ecological role: Herbivore
Shock sensitivity: Medium
Calcium and minerals: Medium
Molting: Shell growth
Reproduction: Oviparous
Compatibility & tankmates: Reef safe

Image gallery

Licensed images linked to the species or, when marked, to the closest representative taxon.

Related species

Recommendations grouped by close relatives, companion choices, and similar care.

Variants and close relatives

Same atlas type, nearby scientific identity, genus, or family.

Acorn dog whelk

Nassarius glans

Species description

Care, breeding and tankmates