This is a great thread, and thank you for that article. I've often wondered about this. I'm in the "smarter than we give them credit" category. Let me give you an example using the Letort, a stream near me. There is a noticeable difference in fish behavior when you approach the stream with or without a fly rod. Locals contend that the fish know you are there to catch them...I'm pretty sure they just think humans with sticks are bad news.

Its not an acknowledgement (which would necessitate reason and reflection), but there is some collective knowledge. To ask if fish are smart is ridiculous. Intelligence doesn't actually exist....humans created that concept and figured out how to quantifiy it. You can say someone is smart, but all you are really saying is that they are "smarter" than a portion of the population. I'm not saying that Einstein wasn't a genius, I'm just saying that he wouldn't have been one if there wasn't someone else there to tell him.

Here's another one. We essentially do the same thing with language. Do fish have language...well if you don't relegate language to the ability to speak...then yeah, they might. Example. They have these eels in NZ. The eels "know" when fish are caught because the fish release pheromones into the water to warn others about predators (i.e. the eel). Its clearly some form of communication (albeit slightly ironic since the pheromone to warn the eels has begun to attract them).