Description

Tridacna maxima

Tridacna maxima is a species of giant clam, often known by the common names:

Small Giant Clam

Maxima Clam

Elongate Giant Clam

Size One of the smaller giant clam species. Shells typically do not exceed 20 to 35 cm (8 to 14 inches) in length, though they can rarely reach up to about 41 cm.

Distribution It has the widest geographic range of all giant clam species, extending throughout the Indo-Pacific, from the Red Sea to the central Pacific.

Habitat Lives in shallow, well-lit waters on coral reefs and atoll lagoons, often partly embedded in coral or attached to the substrate by a byssus.

Mantle Colouration Highly prized, especially in the aquarium trade, for its brilliant and variable coloration which includes blues, greens, browns, and yellows. The colors come from crystalline pigment cells that protect the clam and enhance the photosynthesis of its symbiotic algae.

Diet It is a mixotroph, getting most of its nutrition from the symbiotic photosynthetic algae (zooxanthellae) that live within its mantle tissue, but also filter-feeds on plankton.

Conservation Status It is listed as Least Concern on the IUCN Red List, but is protected under CITES Appendix II, meaning international trade is monitored and requires permits.
Would you like to know more about its role in the coral reef ecosystem or its popularity in the aquarium trade?

Tridacna maxima is one of the most popular and highly sought-after invertebrates in the saltwater aquarium trade, prized for its manageable size and spectacular, vivid mantle coloration.

Vibrant Colouration: The primary appeal is its stunning, often electric-colored mantle. Maxima clams exhibit some of the most intricate patterns and brightest colors in the genus (Tridacna), including vibrant blues, greens, purples, and golds.

Manageable Size: Unlike the true giant clam (T. gigas), which can exceed 1 meter, T. maxima typically reaches a maximum of about 20-35 cm (8-14 inches) in an aquarium. This size is suitable for most home reef tanks (usually 55-75 gallons minimum recommended for a long-term home).

Reef-Safe Filter Feeder: It is a valuable member of a clean-up crew. As a filter feeder, it helps to remove particulate matter, ammonia, and nitrates from the water column, contributing to overall water quality and stability.

Aquaculture Success: A significant portion of the T. maxima sold today is aquacultured (farmed) or maricultured. This shift from wild collection helps reduce pressure on natural reef populations and often results in hardier, pest-free specimens that are better adapted to aquarium life.

Key Care Requirements (High Demand Species)
While popular, T. maxima is generally considered an intermediate to advanced clam species to keep due to its strict environmental needs.

Lighting High Intensity is Critical. This clam relies heavily on its symbiotic algae (zooxanthellae) for nutrition, which requires intense light for photosynthesis. They need Photosynthetically Active Radiation (PAR) levels typically above 250 mol/m/s in the clam’s placement area.

Water Quality Stability is Paramount. T. maxima is highly sensitive to fluctuations and poor water quality. Parameters must be stable, especially:

• Calcium: 400-450 ppm
• Alkalinity: 8-12 dKH
• Magnesium: 1250-1350 ppm

They consume Calcium and Alkalinity rapidly for shell growth, requiring consistent supplementation.

Water Flow Moderate and Indirect. It prefers good, consistent water circulation to deliver nutrients and remove waste, but the flow should not be a direct, blasting current that could damage its delicate mantle tissue.

Placement Attach to Rockwork. T. maxima naturally anchors itself to hard substrate (rock or dead coral) using strong byssal threads. They should be placed on a piece of rock or an elevated clam holder, not directly on the sand bed. Crucially, never forcefully remove a clam from its attachment as this will damage the byssal gland and likely kill the clam.

Feeding Supplemental Feeding May Be Needed. While larger clams are largely self-sustaining through photosynthesis, small juvenile clams (under 4 inches) rely more on filter-feeding and often require supplemental feeding of phytoplankton 1-2 times per week.