Crocea Clam : Tridacna crocea

Phylum:  Class: Order: Family: Subfamily Genus: Species:
Mollusca Bivalvia Venerioda Cardiidae Tridacninae Tridacna T. crocea
Common Names:  Crocea Clam

Scientific Name:  Tridacna crocea


The T. crocea clam is one of the most attractive clams and is easily confused with T. maxima.  Color can be a combination of blue, purple, yellow, green, brown, gold or orange in various patterns.  The mantle usually has numerous iridescent blue, yellow or green blotches or lines.  T. crocea has a very large abyssal gland (larger than T. maxima).  This gland is used to anchor the clam in the strong water currents they inhabit in the reef crest. The shell is thicker than other clams, relatively small folds on the side of the shell and small scutes usually on the upper portions of the shell only. Incurrent siphon has very fine tentacles.  T. crocea is the smallest of the ‘giant’ clams and reaches a maximum length of 6-9″ in the wild and is usually under 5″ in the aquarium.

Natural Environment:

Indo-Pacific in shallow areas near shore where they burrow themselves into the substrate and coral heads.  Only the top of the shell and mantle are visible once embedded.  T. crocea clams can be either wild caught or tank raised.  Tank raised specimens usually have larger scutes. 

T. crocea is a fairly delicate clam and is probably one of the most difficult to keep long-term in captivity.  Adequate lighting is key to keeping these clams healthy. 

T. crocea is a light loving clam and requires the most lighting intensity of any of the clams, preferably 400W metal halide or high intensity LED.   Under insufficient lighting, the mantle coloration may fade or turn brown.  Extensive mantle extension may indicate a lack of light as the clam attempts to maximize the lighting exposure by extending to the fullest extent possible.  Since Crocea are shallow water species, they may tend to do best with lower Kelvin lighting (6K – 10K).

Water Current:
Moderate to high (but not direct laminar) water current.

None.  Need to keep it away from aggressive neighbors.

Primarily photosynthetic.  They may benefit from feedings of phytoplankton, but it is not required.  Very young clams under about 1″ in size seem to depend on feeding more than older clams, so it is best to avoid the very small specimens which have a poorer survival rate than the larger clams.

Supplements & Water Chemistry:
Salinity should be maintained between sg 1.024 and 1.026.
Alkalinity should be maintained in the dKH 7-12 range
Calcium should be maintained at 400 ppm or higher.
pH should be maintained between 8.1-8.4

Does well within a range of at least 74º to 84º F

Tank Positioning:
Can be positioned on the substrate in the bottom of the tank in a moderate to higher water flow area if intense lighting is provided.  Otherwise position higher up in the tank in a secure location where it is not in danger of falling (jumping) in order to ensure it gets adequate lighting.  T. crocea have a foot that they can extend out of the shell and use it to re-position themselves if they are not happy where you put them initially.  If placed on a solid surface, once settled in they attach themselves permanently using byssus threads. This makes them difficult to near impossible to re-position without risking damage to the clams when place on large pieces of liverock.  That is one benefit of keeping them on a soft substrate where they cannot attach or placed on a small rock where the clam and rock can be moved together if needed.

T. crocea clams in the hobby are predominantly farm raised now.  This farming is only done where the clams live naturally and is not practical for the home propagator to attempt.

Header picture courtesy of Nick Hobgood.  All other photos by ReefCorner © All Rights Reserved