Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Posts: 11,721
Super glue, the gel formula works best.
Stainless steel screws, or marine grade. I have marine grade hose clamps that do not rust.
If you want to tie plants in place, cotton thread will rot, which does not hurt anything. Polyester or nylon does not rot, and might cause problems for the fish if it comes loose.