Yea...
Also..ribbon eels are very good at escaping...along with other eels. So make sure your tank is properly secured.
If your eel seems to be losing weight and not eating..drastic measure could include force feeding...whereby the mouth is opened gently with your hand and a small food item fed to the animal. Take care not to feed too big a portion..as the digestive system can be overloaded all of a sudden. Not a recommended method for very very weak animals.