Tridacna gigas is almost completely photosynthetic even at small sizes. My friend Cyril has NEVER fed his ever; it's always been under PC's (just about a year now, first in a 10 gallon nano, now a 33, always on the sand) and has doubled in sizes from 2" to 3.75".
Other clams like maxima and crocea are likewise less food dependant, relying mostly on their zooanthellae. But keep in mind that they are far more light demanding than the clams like the hippopus and derasas, which will more than likely exhibit very reduced growth without feedings of phyto.
Size is one thing, species selection is another. Keep that in mind when choosing a clam.
__________________
This and that.
|