About a year ago, I saw a four-inch writhing creature holding its own in the current at my LFS. It looked anorexic by shape, because it had a fat tail and huge jaws, but a thin neck which gradually widened into a body. However, it was not near death's bed, as it's body showed no surface signs of starvation. It did not seem responsive, it only wiggled rhythmically, making an 's' shape as it undulated in one place. It's head was a distinct triangle. It was not even as thick as a pencil. Gray color. Eating bloodworms at the time. Any guesses?