Yeah! a great Christmas result.
Congrats!
However... You need some serious rock work. That is.. um .. not good. You need an arch, some nooks, crannies, tunnels, and caves. Otherwise, the viewers will have no exploratory viewing possibilities which artificially reduces the tank's visual size and impact.
You should have that rock actually reach the surface somewhere as that projects 'depth' to your display and allows shadows. You want the tank to look as different as possible from various sides. Every side that looks different increases your tanks interest and viewing pleasure by - another tank! I think your tank should look like perhaps 4 tanks as every side should be different, else wise you will have just a monaural tank instead of a 'surround sound' tank, if you get my meaning.