Dont listen to moliken. I havent had a chance to try yet. I got a new job recently which has me working all kind of hours, i tore down my tank because i didnt have time to take care of it.
You prob wont be able to do it in a 55gal tank, but there are other methods to coax it into happening and methods i have read and documented online to help increase their survival.
Just because there isnt any known home hobbyist doing it, doesnt mean it cant be done. There are many commercial establishments doing it, and they are doing it on a big scale. And by saying, "It cant be done" doesnt provide any insight as to why other than they dont think it can be, which is an opinion, not fact.
They used to say we couldnt go to the moon and that the world was flat.
Its going to take several tanks, and some neglecting of the clams to get them to breed and you have to have time to watch the new borns and keep great water conditions. Then getting them to take on the zooplankton i havent had a chance to test out ideas but there are methods posted on how to do that as well, but a bit inhumane.
Hopefully, when i can get some time away from my current job and starting my own business, i'll be able to give it a shot.
I've got a plan drawn up of the equipment i think I'll need, but finding the time to babysit is the issue.