Hello,
I'm also a nooby, but from my "Marine Invertebrates" By Ronald L. Shimek, PH.D. oysters feed on substantial amounts of phytoplankton. Must be oriented in the position they had when collected, as they have good balance sensory organs and will become stressed if positioned upside down or at odd angles. Do well under reef normal conditions. Perfect animals for a tank where the low-light intensity would help prevent algal fouling. Predatory animals, such as shrimp, crabs, hermit crabs, whelks, and "nipping" fishes will impact the animal, feeding on its exposed tissues. Also need 50gal or larger tank. Hope this helps some. Maybe on the reef board they will know more.