Try going to <a href="http://ipsf.com/," target="_blank">http://ipsf.com/,</a> the have fauna kits there. They are commonly referred to a detrivore kits. They contain little critters such as Amphipods, copepods, etc.
Alot of people recommend them only to be introduced to well established tanks. A time period may be recommended, but it really depends on the amount of live food available in the tank. If there is not enough live food, pods, etc. these fish will starve to death over a few weeks to months. It is recommended you only purchase plump well fed ones. They can live on brine shrimp for a short period of time, but pods are recommended for their survival. It really is a shame when these beautiful fish are sold to customers who really do not know what and/or are not able to supply them with proper food.
If you cannot properly feed or care for this fish, please return it your LFS until you tank is ready for one.