There are several products to consider. Regular drywall, green board ( a moisture resistant drywall used on bathroom walls, it's green), Durock ( a cement mixture sandwiched inbetween two layers of mesh, typically used behind tile). I wouldn't recommend using Dens Glass ( fiberglass drywall, it's mainly used for exterior applications, it's yellow). Unless you're familiar with hot mud AKA Quick Set, I'd use regular taping mud. Hot mud usually sets up in about 20 minutes, and if you don't have a quick taping hand, you may end up sanding alot. Plus hot mud has a tendency to shrink a little. Just take your time, maybe practice with the mud a little bit in the garage before you go around the tank. Read up on hanging and taping, there's a lot of references out there. Good Luck!! Dave