Hey wlbadger,
I once had a Midas cichlid (Amphilophus citrinellus) that was every bit of 14". This fish hated me. Now my wife could do anything in this fishes tank, in fact whenever she would approach the tank he would come to the front and "mouth" the glass as though he was kissing it. True Story.
In answer to you question...YES larger fish will sometime try to take a bite out of you...especially if their hungry or protecting a spawn of fry.
As for doing maintainence, I would simply "nudge" him away from me with the siphon tube. Do not get distracted though as this can and prolly will lead to a nip from him.
Larry