Are fish happiest, in the wild? (Details.)

I wasn’t sure how to phrase this question.

I’m curious if fish are unhappy with life in an aquarium. I know that they can be more stressed, under certain conditions. I have read that constant light, people knocking on the glass, lack of hiding places, even lack of other fish can be stressful.

Life in the wild must be stressful too.

Are fish happier in an ideal aquarium setup, than in the wild?

Do fish have the slightest concept of “happiness?”