Looks like found my answer
"For the most part, the ornately colored species available in aquarium stores — most of which belong to the family Chromodorididae — do poorly in captivity unless they are provided with their natural bill of fare. For example, Kunie's (Chromodoris kuniei), Bullock's (C. bullocki), Loch's (C. lochi) and Elizabeth's (C. elizabethina) nudibranchs, which are the species most commonly encountered by hobbyists, all feed on sponges. If they are not provided with encrusting sponges to browse on they will become inactive and die."