Goldfish not smart?!
http://www.fish-school.com/
Yeah that may 'just' be conditioning with food, but isn't that what intelligence is - problem solving for the sake of necessity or want? We aren't talking about scientific reasoning, that is pretty much a western thing.
I guess it is like Nagel's Bat... the philosopher questioned "What is it like to be a bat" and subjectivity basically leads to the idea that the only possible way one may know what it is like to be a bat, is to be a bat
I think based solely on territorial behaviour, sexual and courtship behaviour, mooching for food, etc., it is easy to deduce that fish are intelligent and have emotion...
Dictionary.com says...
Emotion: .any strong agitation of the feelings actuated by experiencing love, hate, fear, etc., and usually accompanied by certain physiological changes, as increased heartbeat or respiration, and often overt manifestation, as crying or shaking.
They definitely feel fear and potentially hate, or at least jealousy/disliking. And these are definitely accompanied by certain physiological changes - ever see a fish get scared
I'm sure everyone with an aquarium has thought about how their fish perceive them... fun stuff

What makes fishkeeping such a noble hobby, in my mind anyways, is that we spend all this time, effort, and love taking care of something that doesn't give us anything in return but living a healthy life and being there for us to observe.