Thanks.
As far as light levels, more is better when it comes to clams. While these are cultured, their wild counterparts are found just a few feet below the surface, under intense tropical sunlight.
We keep our clams in our greenhouse initially without supplementation. We transition them to LED with Par levels 150-250, typical of what most folks might have in their tanks. In systems with some nitrate and phospate they do well, many folks report they do better if you have a well fed fish population, due to higher nutrient levels. I do not find that additional supplemental feeding is beneficial.
When we bring in clam shipments we bring large numbers to make the freight and misc. costs work out. We generally hold them at least a week and often 2 weeks before we offer them for sale. It can take that long or longer for them to fully open and adjust after shipping. We normally have zero mortality during this transitional phase. Sometimes I'm a bit impatient and try to take pics for the site before they are fully transitioned and you may occasionally see some pics where the mantle is not fully expanded, it is difficult to get a good pic of them without disturbing them and having them naturally retract.
The clams originate from farms in the South Pacific. I helped set up a couple of the farms many years ago. The clam shipments transit through Los Angeles where many wholesalers are located. These wholesalers sell the clams immediately and do not allow them to rest. Our clams simply transit through Los Angeles and come directly to us in Maryland without going to the wholesalers. This results in less handling and allows us to control the acclimation and transition process. The transition phase when they first arrive is critical to long term survival. They must be rested. Initially they are extremely reactive to light and it is a transition from sunlight that they are grown under at the farms to artificial light used by hobbyists. We keep them initially in our greenhouse then transition them to LED lighting once they are less reactive and more settled. We received a shipment of Blue Maximas last week and probably will be next week before we post them for sale.
Thanks!