Center brace for 55g broke...

[Pomatomus]

i would silicone a piece of scrap plastic, or glass, or whatever to the underside of the broken brace, and clamp it together until dry. Or just order a new top frame from glasscages.com

^
you could also put some screws through that scrap plastic if you're worried about the adhesive

 

[Pharaoh]

I just drilled to holes on either side of the brace and then installed screws and a metal bracket across the brace. Worked like a charm.

 

[gomezladdams]

If theres enough room you can use some stainless steel machine screws and a piece of plexiglass to join the broken ends.Otherwise its cheap enough to get a new frame.