Derasa Clam

Derasa Clam – Tridacna derasa

The Derasa Clam, occasionally called the Smooth Clam or the Southern Giant Clam, is a large, smooth-shelled Tridacnid reaching up to 24 inches in the wild, with aquacultured individuals commonly displaying gold, brown, orange, and yellow mantles trimmed in vibrant blue or green. Its shell features six to seven vertical folds and a narrow byssal opening, distinguishing it from T. gigas. Peaceful and stationary, this clam relies heavily on light-driven symbiosis with zooxanthellae and can grow rapidly when kept in proper conditions.

A well-established reef aquarium with moderate to intense lighting is essential for keeping T. derasa, as they derive most of their nutrition from photosynthesis. Place them in the sandbed or a shallow rock recess, and carefully acclimate smaller specimens (under 2") to bright lighting. Maintain stable calcium, alkalinity, and magnesium levels to support healthy shell growth.

While larger clams (over 2") typically do not require additional feedings, smaller Derasa Clams benefit from PE Cyclopods or Hikari Rotifers several times per week, especially in low-nutrient systems.  Occasional feedings of phytoplankton, such as Reef Nutrition's Phytofeast, can encourage healthy growth.

Approximate product size (in inches): Varies by selection (commonly 2–4").