The function of the fish tank is to produce "steam". Where water is needed in geomantic omen (often to promote wealth or control evil), it is usually placed in an angry position or when the stars fly. Because your position is in the middle of the house, there is no restriction.
From the layout point of view, it is possible, which has both decorative function and the function of isolating the dining room and living room into another space. The god of wealth tree and the fish tank are facing the entrance passage, giving people a very cool feeling!
For reference.