Bamboo shrimp are good. They're filter feeders and need an established tank so they have enough food. Some Macrobrachium sp. are also great but they can catch and eat smaller fish.
Mine seem pretty rock solid and I've had them for over a year. I don't do anything special to the tank other than weekly wcs and I've never had a problem. Their tank-mates are angels, rainbows, cories, SAEs, BSNs, and briggs and everyone gets along great!