I would say that the asian snakehead is more like the slaughter fish, there's also a prehistoric fish that really looks like a slaughter fish but the name eludes me at the moment
There are alot of fish.. and crocodiles... that look like slaughter fish. A real slaughter fish would look like this, exept the mouth need to be extended a little bit longer http://creepyanimals.com/2011/08/goliath-tigerfish/
You'd definately see some real Slaughterfish if you watched "River Monsters" on Animal Planet. That picture that AzureFlames0 linked to is from "River Monsters", when Jeremy Wade fished up a Goliath Tigerfish, a fish that is capable of taking chunks out of Crocodiles. Jeremy Wade pulls up some truly massive monsters on that show. Really makes you think twice about going swimming in a river or even a lake again. Especially when he fishes up Bull Sharks in inland rivers.