is pretty heavy, I would engineer the stand to take at least 1000 lb.
I don't have any pics for you since I built my stand out of wood (rail & stile with plywood panels) so the load is carried by the frame. However, I have built a wood working table out of plywood, and the plans appears solid.
The wood working table plans calls for 1" plywood for strength & rigidity. If you can't find 1", you can glue 2 3/4" together (with the undersized plywood these days, 2x3/4" is just over 1.25"). Instead of just a simple box, this stand is heavily reinforced. (If you look at a standard kitchen cabinet, that is just a simple box & not strong enough for 1000 lb).
This table has solid sides reinforced at each corner with 2 - 6" plywood legs jointed in a L shape (I used a rabitted joint for stability). The front & back is open, but the top is supported by 6" plywood rails at both top & bottom (& front & back). The thick rails prevents racking movement, while torsional stability is provided by the top & bottom shelf. So far this table had withstood lots of pounding & general wood-working abuse & is rock solid. A design like that would be something you should look into.
Note the table is 4'x6'. All parts are glued & screwed together. You will need to size things to fit your tank. With a glass tank, you can omit the top, but you'll need to put braces (maybe 12" wide x3) front to back to give rigidity). The tank should sit right on top of the sides/rails. You might consider adding extra legs down the middle as well to prevent sag (although the 4 6" rails make it pretty rigid.