If your Mrs doesn't like getting nipped, the only way to reduce it is to catch out as many HBG as possible, now. If the nibblers spawn, only a total kill off will put an end to surprise attacks from under the water!
I don't think RES are known to nip much, but stocking more will not impact the HBG. I think you are fine right now on RES numbers. The combination of YP and SMB would do well without the HBG also. One other addition might be a few HSB in a year or so....
