Electric Flame Scallop

Photo: Wikimedia Commons (CC BY-SA)

Ctenoides ales

Identification	Small bivalve with a vivid red-orange mantle fringed with numerous tentacle-like projections. The most distinctive feature is a rapid, repeating electrical-flash effect along the mantle edge — caused by light reflecting off rapidly moving tissue, not true bioluminescence. Also sold as the Disco Scallop or Electric Scallop.
Maximum Length	3 inches (7.5 cm)
Origin	Indo-Pacific — widespread in tropical reef environments; found tucked into crevices at 10–80 feet depth
Minimum Tank Size	30 gallons with established live rock and low-flow areas
Reef Compatibility	Yes — reef safe

Behavior

A free-living, non-sessile bivalve that roams the aquarium using jet propulsion — rapidly clapping its shells to move short distances. It will eventually settle into a dark crevice or overhang in the rockwork. Unlike Tridacna clams it has no photosynthetic zooxanthellae and is entirely dependent on filter feeding. The electric flashing display is a defense mechanism used to startle predators. Considered a challenging species long-term due to strict dietary requirements.

Diet & Feeding

Strict filter feeder — requires a consistent daily supply of phytoplankton and fine zooplankton. Feed live or frozen phytoplankton (Nannochloropsis, Isochrysis) daily. Rotifers and coral-food blends also benefit this species. A mature refugium with active phytoplankton and zooplankton populations significantly improves survival.

Cautions

Challenging long-term — most decline without dedicated phytoplankton supplementation. Not recommended for new reef keepers. Avoid strong direct flow on the animal.