One of my clows i have had for three years, the other for 9 months....they jsut recently paired up and decided to host...they picked a nice rock with blue shrooms and pumping Xenia...some clowns like soft corals....i have heard of them liking fuzzy shrooms, mine prefered the regular ones. also i have heard of them hosting frogspawn and bubble corals. maybe get a few of those corals, give them some options....They may not host untill they want to spawn.