The Snakehead fish is an invasive species originally from native parts of aisia and africa . however there is another species of the stonehead fish that is thought to be from other parts of the globe such as china. The stonehead fish is a top predator among its food chain and will eat small mammals such as rats, amphibians such as frogs and even other fish ! However when they are young they will mostly feed on plankton, sea insects and mollusks
Yes, you absolutely can, the snake head fish meat is nice and thick. Though I couldn't personally recommend eating it
A new animal introduced to an ecosystem can cause a multitude of issues or do nothing at all only time will tell however some consequences could be that some animals go extinct or become endangered among other things such as less wild life diversity, or maybe they can become a good source of food for wildlife and people a like we will see how it turns out.