As was noted, I would worry more about the stucture of the floor I was putting it on. Also you need to think about what temperature you need the water. I dont have experience with a tank that large, but it would probably be expensive to heat. You could probably set up some sort of a pump, float system to help with the water changes. I don't know about live plants, you would need some pretty powerful lighting to penetrate deep enough for plants to flourish (?) You should also consider how you will treat the tank if an illness or parasite breaks out. Would take a lot of product I would think.
Have you considered using native species like perch ( there are different kinds of perch, some are colored with patterns), catfish, bass, crappie ect? You might put some crawdads on the bottom or even try a freshwater turtle or a couple bullfrogs. You could do a net search to find out more. Koi would do well in a large tank. Trout must have cold water to survive. Keep in mind that you can buy chillers as well as heaters. I dont think any of these fish would be too picky about the temp or water hardness.
If you put in things besides fish, like turtles for example you will need to make adaptions for them such as lighting, and a floating stabe piece of 'land' for them to come out of the water on.
Just some ideas.