I'd think the reds would work like a razor blade would.. as long as you dont orient the blade in a way that its gunna scratch the glass, you should be fine..
55g - Planted/PFS - Up and running as of 4/30/06, heavily planted running 2x 175 metal halide, dry dosing.
lots of fish.
10g Freshwater - Fake plants/PFS -
Breeding pair of convict cichlids purchased from the LFS I work at for $1.25
(best part is that I have a place to get rid of the fry!)