Recently a type of bird has been observed on the banks of the Luo river in Luoyang China. The bird is wholly white has an elongated neck and preys upon small fish. What might be the name of this bird?

Sharp shinned hawk, kestrel.

Yes, but there usually small Bird of Prey's

First of all, the smaller birds are likely trying to defend a nest. Red-Tailed Hawk vs American Kestrel for example, I have seen it happen. As to why the larger birds don't fight back, I'm not...

It is a perching bird (passeriform), and is considered a songbird.

One of the birds that prey on smaller birds is the Peregrine Falcon which can dive at speeds of 300 KPH right on to prey! The fastest a Peregrine has ever gone is 400 KPH!