I'm reading it cause it's about fish and it was $2.99 at the goodwill thrift store lol. It's pretty informative so far. I just finished Chapter 2(of 37) and the first 6 are about physical characteristics, how they move, why they move the way they do, how they breathe, how they float and so on. The swim bladder is connected to the ear btw.. if they have a swim bladder that is.
The authors at the time of publication were working on making a fish screen for aqueducts that would allow smaller fish (specifically focused on fish in the 4-8 cm range and the delta smelt) to escape and not get sucked onto the screen and die.