What kind of blenny?
I have a SFE with 2 clowns, ember blenny, psudochromis and he bothers no one. They are not fish eaters, they are more of crustacean eaters thats why their teeth are different then other eels. But as Steve says you need to keep him fed because if he gets hungry then all beats are off.
I made a pile of LR
just for my eel so he has his own home and dose not bother anyone else.