Check out Loctite PolySeamSeal Caulk+. It's an adhesive/caulk that dries crystal clear. I used it to attach some painted MDF mirror frames I made to the mirrors. I think it would work perfect for your application where the tank does not need to hold water like an aquarium would. I picked it up an either Home Depot or Lowes, I can't recall which one as I shop at both on a way too regular basis.
Basically, a tool is an object that enables you take advantage of the laws of physics and mechanics in such a way that you can seriously injure yourself - Dave Barry