This book intended to teach the lesson of sharing however, there are so many wrong concepts in this book that just worries me as a parent. First - if you want something from someone and the person refused to give it to you, you tell everyone around you and get them to unfriend, outcast and ostracize the individual. Seriously?!?! Second - if you badger someone long enough, you will eventually get what you want. Third - you must share in order to be welcomed and accepted, even if that means giving away a part of you. Fourth - when you're no longer unique, the world is a happier place because everyone is now equal.
I get the part about sharing but how the book "forced" sharing upon the rainbow fish is what I cannot agree with. And one should never encourage herd mentality to peer pressure or ostracize someone because they refused to conform to the norm. All kinds of wrong I'd say.