I only know of the "evil" kelpie, a shape shifter, but normally a horse if an animal; an evil spirit that would drown you any way it might manage to. Am I sensing another story?
Some eels do make some noise; more like a pitchy grunt than a screech. Or is that lung fish?
The only thing you can do about it is make some sushi rolls while the kelp and eel are still fresh... (ha, made you read it 
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