Spotted drums are fairly slow swimming, about the same as a large angelfish. They cruise the reefs (and the aquarium) casually searching for something to eat. They are usually bottom feeders, and mine will scoop up sand in its mouth looking for small organisms. They also learn very quickly to grab food out of the water column. Mine loves Hikari 'A' pellets soaked in Selcon above all other things. They also chase and eat very small fish and shrimp, in capitivity and on the reef. They will eat almost anything, with gusto.
Spotted Drums love caves, and really need them to settle down. I have more than 200 pounds of live rock in the 220, arranged into 4 large open ended caves, through which the Drum swims in constantly changing circular patterns. Spotted Drums are very peaceful, except with another Spotted Drum. In an aquarium, two would result in a certain fight to the death. The adults are solitary, except in breeding season, when they will pair up. I've observed them on the reef for many years, all over the Caribbean.