Hi
Depends on what kind of starfish as to diet. Tropical species are easier to keep as it's tough to keep water cool enough for cold water types. A tidepool rather than reef setup is also fascinating in a much different way.
I have always had a fascination with Crinoids .feather stars which swim rather than creep. They are filter feeders though and very sensitive to water quality.
Would guess that most people collect them for the dried specimens but wow what a waste of such a gorgeous creature lol gary

You can fish them tablet fish food, they love Tabimin, place a Tabimin and put the starfish on it.

Tabimin? Cool! A lot better than coral!

The only starfish that eats coral is the crown of thorns, the others are either filter feeding or molusc/detritus eaters. Filter feeders can be fed with liquid food, molusc/detritus eaters do well on Tabimin.