Not sure if this info helps but i have a skeletor eel (Echidna xanthospilos) which is a pebbletoothed dwarf moray and is about as reefsafe as your likely to find,I believe they can reach about 2 feet in length,mine lives in a cave with a cleaner shrimp & a green chromis and for the last 6 months has shown no interest in any livestock but its my guess he'd make a quick meal out of any small crabs or shrimp other than his pal the cleaner,I suffered from a bad breakout of ick which killed my angels & a small bristletooth tang but the eel survived with no problems and after speaking with a marine chemist for a well known UK remedy brand he informed me that eels don't suffer from spot the same as fish but they also don't tolerate copper treatments (not sure if this is relevant,just handy to know).
mine lets you know when he's hungry and is pretty active when its dinnertime,definitely cover the tank as i don't think I'd have had him this long without covers,i also modded the top of my weir to stop him setting up home in there,also worth a mention is the amount of waste from him (unreal) i programmed my mp40s to run nutrient export twice a day which helps,without this facility i guess just plenty of flow to stop detritus settling but I definitely recommend keeping one very cool creatures