What are the benefits of ornamental fish Seven Star Knife in Feng Shui?

Seven-star knives, like dragon fish, maps, etc., have strong evil spirits. A few seven-star knives produce less evil spirits. If hundreds of them are raised in a large fish pond, If you use a seven-star sword, the evil spirit generated will be stronger. But it is impossible for ordinary people to keep so many fish. In fact, they are just fish lovers who like to keep them. They can only be regarded as ornamental fish.

It is said that this kind of fish with strong evil spirits is good for people who work in side industries. But I don't think so, because

There is no scientific medical evidence.