ORA Hippopus Clam

Quick facts

Identity

Also known as

Horse Hoof Clam; Bear Paw Clam; Strawberry Clam; Horse's Hoof Clam; Giant Clam

Synonyms

Chama hippopus

Environment

Saltwater

Native to

Indo-Pacific, Indonesia, Palau, Philippines, Australia, India to Kiribati

Habitat

Shallow reef flats, seagrass meadows, and sandy or gravelly lagoon floors across the Indo-Pacific.

Sourcing

Aquacultured

Conservation

Vulnerable

Care

Care level

Moderate

Temperament

Peaceful

Adult size

2 – 14 in (5.1 – 36 cm)

Lifespan

10 – 30 yrs

Min tank

40 gal (151 L)

Growth rate

Fast

Placement

Bottom

Water

Temperature

72 – 78 °F (22 – 26 °C)

pH

8.1 – 8.4

dKH

8 – 12 dKH

Salinity

1.023 – 1.025 SG

Flow

Low-Moderate

Behavior & compatibility

Social

Solitary

Aggression to own kind

Low

Active

Daytime

Reef safe

Yes

Invert safe

Yes

Shrimp safe

Yes

Clean-up role

Filter feeding

Population boom risk

Low

Feeding & breeding

Diet

Photosynthetic

Foods

Phytoplankton, Zooplankton

Breeding type

Broadcast spawner

Breeding difficulty

Not bred in captivity

Sexing

Protandric hermaphrodite; functions as male when young and develops female reproductive capacity with age, no external sexing possible.

Target feeding

Beneficial

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Care guide

Overview

Sits directly on the sandbed rather than draping its mantle over the shell edge, exposing golden tissue marked with fine pinstripes and purple or green dots. The thick, ridged shell tolerates a wide range of lighting and moderate flow, drawing most nutrition from zooxanthellae with occasional phytoplankton dosing. Stable calcium and alkalinity support its fast, heavy shell growth.

Care

This clam is one of the hardier giant clam species offered in the trade, tolerant of a wider range of lighting than Tridacna species. It should be seated directly on an open sandbed rather than perched on rock, since adults lose much of their byssal attachment and rely on body weight to stay in place. Stable, elevated calcium, alkalinity, and magnesium are needed to support its thick, heavily ridged shell, and water changes should avoid sudden salinity swings.

Feeding

Most nutrition comes from the zooxanthellae housed in its mantle tissue under adequate lighting, so direct feeding is supplemental rather than essential. Juveniles benefit from occasional phytoplankton dosing a few times a week, while adults are less dependent on it. It also filters fine particulates and processes ammonia and nitrate from the water column, contributing to overall nutrient export in a reef system.

Tank mates

Because the mantle sits flush with the shell rather than draping over the edge, it presents less exposed tissue to mantle-nipping wrasses, crabs, shrimp, and pyramid snails than a Tridacna clam, though it is not immune to such predation. It coexists well with typical reef fish and invertebrates and does not sting or compete aggressively for space. Avoid placing it where it could be knocked over or buried by burrowing tankmates or shifting sand.

Breeding

Spawning has been achieved in aquaculture facilities using hormonal induction or temperature and light cues, but it is not practical or reliable in home aquariums. Fertilized eggs develop into free-swimming veliger larvae that require intensive larval culture with algae feeds before metamorphosing and acquiring zooxanthellae. Most specimens in the trade are aquacultured from commercial clam farms rather than bred by hobbyists.

Health

Watch for pyramidellid snails, which can parasitize the mantle and cause a clam to appear weak or gape excessively. A healthy specimen extends its mantle fully during the day and reacts to shadows or sudden movement by contracting; sluggish or incomplete mantle extension can signal stress, poor lighting, or water quality problems. Sudden gaping without response to stimuli often indicates the animal is dying or already dead.

Sources

1. Hippopus Clam - Quality Marine
2. Horsefoot / Bear Paw Clam - Reefs.com
3. Horse hoof clam care: tank size, temperature and tankmates - TankBud
4. Hippopus Clam, Aquacultured - LiveAquaria