Well- interesting piece. It almost certainly wasn't used as a fish hook though... it just wouldn't have worked. These things have been called fish hooks since the beginning of time I think but mostly due to the fact that people just didn't know any better and they had the right shape so the missinformation has been passed down from generation to generation, the truth of it is though if you tied a line to this and actually tried to fish with it you would starve to death before you caught a fish or lose the hook. Now if you don't believe me I will knapp out a decent hook like this one and send it to you to use for fishing and we'll see. In addition to that, I don't believe there is any correlation what so ever with these hooks being found in streams or lake bottoms or even shoreline sites for that matter (that I know of anyway). Sooo.... what was were they used for? I'm not sure anybody knows... some people still argue fishing hooks (Note: there's plenty of authentic fishing hooks, but made from bone, antler, and copper, not stone IMO), some say they were suspension hooks, I find that idea much easier to swallow as a line could be better secured (without always being soaked in water as a fishing hook would be) and perhaps used to hold cooking pots over the fire or hang things up in the house or whatever, still others argue that they served other functions as odd tools, charms, etc. although in lesser numbers.
The other thing about these and eccentric pieces in general is that there are a lot of fakes on the market... they tend to bring a pretty good price since they are so rare and I would estimate that at the current time there are likely more fake eccentric pieces on the market than there are authentic ones. This one looks authentic to me but it's impossible to tell from a pic and maybe even in person as some of them have gotten so good at it. This one appears to have a decent patina and everthing so I say cool piece man! I would just hesitate to label it as a fishing hook-