Option 1, look inward from the door, at a 45-degree angle on the left or right.
Option 2, look inside the door opposite (porch).
Matters needing attention in fish tank placement:
1. There is a wall behind the fish tank.
2. the fish tank does not hinder the line.
3. The fish tank is not facing the toilet door, stove mouth or shrine.
4. mantissa: one or three or four. (Reference)
5. Color: green, black, or green and black. (Reference)
6. Fish species: goldfish, lucky, parrot, silver dragon, map, koi fish, my favorite. (Reference)