Usually mine is every 2-3 days. If he is out and wandering around, I feed him right away knowing that he is probably hunting and I don't want to deplete my inverts. Some SFE's might eat every day and others might eat every few days depending on how old/big it is. If it is a relatively young SFE, as mentioned above, they go through growing spurts and will chow down more than usual. My eel is a messy eater and others may be as well so if you do feed frequently, watch for excess waste that will effect your water quality.