Can you put the fish tank next to the toilet?

You put the problem under the classification of flowers, birds, fish and insects, so let's not talk about Feng Shui first, and simply analyze it from the perspective of fish farming:

There are water supply and drainage pipes in the bathroom. This will provide great convenience for changing water. I just siphoned the waste water directly with a short hose, and then filled the water tank directly with the hose connected to the water purifier. The whole process is very convenient, and no basin is needed. In addition, there are more masonry under the floor of the toilet side, which has better bearing capacity and is safer for large cylinders.