The door of the house I bought faces northeast and southwest, but some Feng Shui experts said that the house is not suitable for fish farming?

Is the house you are talking about a building or a courtyard-style house?

A courtyard-style house is quite good for raising fish in the yard, just choose an appropriate location.

This has nothing to do with the direction of the house. It just needs to grasp the direction of the fish pond.

In fact, it doesn’t matter whether you keep fish in a building or not. The fish tank is relatively small, so even if you grasp the orientation well, it won’t be of much use. Of course, this has nothing to do with the orientation.