I have 2 large pieces of holey rock that I silconed to plexiglass. The gravel covers the plexi and cannot be seen. This is a new tank, 1 month old, so I'll see how well they hold together.
Finally got around to taking pics of my setup. None of the rocks are siliconed, I just made sure they all touch the bottom glass, and that they are stacked very stable. The two larger rocks on the right are about 65lbs each, and total about 250ish pounds of rocks.
4 geophagus surinamensis
6 red eyed tetras
3 banjo catfish (hidden)
2 horsefaced loaches (hidden)
1 firemouth
1 veil tail bristlenoce pleco
1 dwarf pike cichlid
1 whiptail catfish
4 kribensis fry
and the sore thumb
1 fire haplochromis ( i think) that is still un identified