It's just as well that they are hard to find. Their diet is very specific as you probably know, I assume you're trying to rid your aquarium of red flat worms. They typically dont do well in aquaria even when a large population of the flatworms is present, and they generally starve before all of the flatworms have been eaten leaving you with flatworms and the premature death of the predator ( Chelidonura Varians ).