Hello, you don't know Feng Shui. From the point of view of fish farming, the position of B is very suitable. As long as the fish tank is not placed in the kitchen or bedroom and there is no direct sunlight, it is ok. The cloakroom is fine. My family also has a cloakroom, which is very convenient.
When 80% homeowners buy fish tanks, the first choice is the porch, which can effectively divide the space.
If you really believe in Feng Shui, look for a Feng Shui master.