Ghost shrimp are usually sold as "feeder" shrimp at pet stores. They can be purchased fairly cheap. We bought ours at a local pet store for about twenty cents each. Although most people use them to feed to larger fish, I think they are pretty cool to keep as a pet. These little guys are a really good clean up crew in any aquarium. Ghost shrimp mostly stay at the bottom of the aquarium and they eat all day long! They sit at the bottom of the aquarium and pick little bits of food out of the gravel with their tiny pincers. Their bodies are transparent and you can actually watch food travel through their digestive tract. They will clean up most of the food that any other fish in your aquarium miss or fail to eat. Ghost shrimp do well with other fish and mostly leave them alone. The only thing you would have to worry about with a ghost shrimp is that it might get eaten if you have a larger fish in your aquarium that eats things like shrimp.
Here is one of my Ghost Shrimp. You can barely see it because of it's transparent body. Notice the dark spot where the food is going through the digestive tract.
Here is a sharper image of a ghost shrimp.
This guy was eating some algae off my plant.
