I have had one for nearly a year. For the first 6 months he just hung around one area of my tank and never ventured far. When I transfered him to the 90 he finally found one of my BTA's and now makes that his home.
They are very neat to watch, they are a filter feeder that changes its feeding mechanism in relation to water flow conditions by using its maxillipeds catching plankton. They will switch these catchers mits depending on the strength of the current from active or passive feeding, using one or the other or both of the maxillipeds.
I would suggest a mature system of at least 6 months with liverock and livesand, if you have a refugium all the better. Mine likes zooplankton in addition to what else is in the water colum. I also use a few drops of micro plankton per week.
Thomas