Pretty average, mostly accurate.
It's not terrible. One phrase I didn't like was, "The BUTTERFLY FISH has been designed to make it very hard to find." It wasn't "designed" by anybody. That's evolution there, Ms. Heller. The majority of the book is just a list of sea creatures that camouflage in various ways.
But for the most part, as far as I know, this is pretty accurate. Octopi and cuttlefish actually do change their color in the way that chameleons are thought to do in popular culture, and then all the other fish that she mentions are just naturally constantly camouflaged. Although I'm not sure that pike fish actually play. "Heads up, the PIKE FISH like to play and with the grasses drift and sway." Yeah, I don't think they're playing. I don't think that's a good description of what fish do. And I'm not sure "predatees" is a real word. She uses it to rhyme with "ease", as in "fade away with ease." Prey. Prey is the word you're looking for here, Heller.
And the last page: "Because the world is hostile, all creatures need protection. They need to hide so thoroughly that they defy detection." Not every animal hides. Elephants, for example, don't hide. Even some prey animals don't hide per se. It also makes it seem like all animals are either predators or prey, and there are many animals, especially fish, that are both. Like the saying, "There's always a bigger fish."