Survival rate of mine - 2 of 2, bought less than 1" long.
Basic tank, 10g, PC with support of direct sunlight, at least twice daily feeding for a filter feeders, smallest zooplankton and finest particles from mysis and grocery seafood, my tank can't handle dried ESV phytoplankton, alas. But green microalgae is growing on the glass walls.
Was a problem to find a suitable place, with side flow, not direct, even reflected from the glass. Then - with bristle worms, irritating one of them, placing clam on shell, not on LR, definitely helped.
Watch it, if not happy - find more peaceful place for it, if don't like one food - offer another. All the same, as with any of inhabitants.
Disclaimer: Not an expert, have only 2 clams and slightly less than an year.