Looks pretty darned solid to me, those 2x4s will take loads of weight when they're under compression (seriously, you should see what we balance on a pair of them regularly). Assuming you were going to have sumps in underneath you might want to sheet in the back so any splashes/water vapour don't get to your drywall, although you're probably ahead of me there. That would also have the side effect of stiffening the uprights so they can't bend over sideways but that's probably unlikely anyway.
2400 lbs sounds like a beast, but the all up weight of the tank is a bit misleading, yes your tank will be heavy, but it's spread over a larger area than most, so I wouldn't be surprised if the load per square foot isn't that far from that of a much smaller tank. As long as you maintain the spacing in the supports, stands should be scalable..
As for the biting thing, as long as it's not treated lumber..
