[Clutchcargo]

Welcome,
You probably would get better responses if you post this in the carpentry section.
You may want to incorporate an angle iron into the design to help resist the flex.

 

[Kap]

Why do you want the fish tank that high? That much weight on top presents a serious tipover possibility.

And how do you plan on maintenance and upkeep of the tank with it so high?

 

[Scuba_Dave]

Hello folks, Im looking into building an entertainment unit. Its gonna be approx 6 feet high and 5 foot wide. The catch is, im putting a 5 foot fish tank on top of it!! I understand the engineering to go into it, THATS ALOT OF WATER weight i know. but what wud be a very good strong wood that u cud reccomend. I need a wood that when it has the tank ontop of it can resist buckling even the slightest bit. This is a MASSIVe project so im not rushing into it or anythin but im tryin to get my research done. any help u have wud be a great help thanks.

Is the tank going to be 5' x 6' also?
How many gallons?
Fresh water or salt?
Will this be on a reinforced concrete slab? Better be
A 6' long, 5' high by 30" wide aquarium is 560 gallons
8.345 lbs per gallon = 4673 pounds
You are probably looking at a steel reinforced stand