This is an ancient work of philosophy, and written in classical chinese. One should not approach such works expecting a ripping yarn, or even for clear advice. 'Always eat your greens' would be unlikely to last 25 centuries, which, on reflection, seems rather a pity. Mankind needs a bit of ambiguity in it core texts, and the Tao delivers, and with a brevity which, (speaking as someone who has hacked through Deuteronomy), could teach other ancient writers a thing or two.
It is, however, very hard to understand. This is a book to ponder and re-read, with the aid of background material, and time to meditate.
I can therefore offer no opinion on why the author, without further explanation, compares ruling a small state to cooking small fish. A quick hunt through wikipedia suggests that translation of this work is an especially difficult problem, and I wonder how much of the ambiguity is down to this.
My few thoughts, such as they are:
1. This seems to be a book aimed at the ruling elite, exhorting temperance, humility and restraint from rulers.
2. It is strongly in favour of allowing nature to take its course, advising against micro-management in rulers.
3. It seems to be pacifist.
4. Many other concepts seems familiar from the Sermon on the Mount, and Plato's Theory of Forms.
5. The book I was reminded of most often was The Prince, by Macchiavelli. Lao-Tze does not seem to have a great respect for democracy.
At the end I was surprised that my reading of a famous religious work should make it seem so worldly. Perhaps that reflects on me. I may have totally missed the point. To try and combat this, my next book will be The Book of Tea, by Okakura Kakuzo, which apparently, among other things, describes Taoism in a more accessible way.