As it is? Most certainly not. Throw a piece of ply on the back? Not much better imo.
But, if you have a few skills you can easily make it stronger. I'd take the top off and where the four thin vertical supports are on each corner, i'd attach four vertical lengths of 3x2. Then add horizontal 3x2 pieces to the vertical legs, all 3x2 lengths to be attached with screws to main dresser frame. A piece of ply on top and another on the back, to help sturdy it up a bit, and that would do it. A bit of wood filler in the screw holes, sanding down and a good lick of black paint, and it should look ok. Not to mention it'll hold your tank. See my diagram to give you the gist of how it could be done.
I'll throw a disclaimer in. This job is probably only worth attempting if you already have some decent wood working skills, otherwise it'll end up looking like something Homer Simpson made!
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