Well the eel that was kept in the guys sump was only about 7-8 inches long so i guess it would be able to hid in my LR but an eel that size, would it have a mouth big enough to eat a 2 in crab?
I really doubt an eel attacked a crab before being placed in the tank, and I especially doubt you have one hiding in your tank...although...I must say...that would be...AWESOME! heh