Can I make this using the pool tool if I wanted it above ground? Or maybe increase the terrain where I want the 'pool/pond' look. What I'm really looking for is to make a home with a 2 story fish tan...
As you can see, there's that little gap between the floors... you could hide it with decorative objects using MOO. But as said, that's the best I can think of.
EDIT: Hid the first pics away in spoiler because this is my best solution for 2 story aquarium illusion above ground... Ground level: build a normal room, copy it. 1st floor: place the copied room on top (= 2 stories). Make the room size pool on the top room - notice: so that the pool is on the above ground room, you have to build the pool on the 2nd floor. Cover all the walls on both floors with windows and place the see-through dance floor to the pool floor. Decorate both floors - which is the most important part of the illusion! Notice that, if you want fish in there by using the fishing signs, the aquarium has to be massive as the fish swim roughly in an area the size of 10x10 squares. Anything smaller and the fish will swim through the walls in the air as in the pics below as the model I made is only 4x6 squares.
Notice: the ground floor room is just a room with windows (no pool) and the 1st floor has the pool.