I used to read that book to my kids, with my own suitable alterations.
The book ends with the rainbow fish -- who has torn off his own scales to give to his 'friends,' swimming happily off to join them in the ocean.
My version, which I read in my best cockney was "But as the now mut'ilated, slowly dyin', rine-bow fish swum off wiff 'is newly purchased mates, 'ee wondered exactly why 'ee wanted those koind of pals."
My wife agreed the book was awful, but she found Dad's version somewhat gruesome for the three and four year olds. [Actually, kids like that kind of stuff.]
Awesome! Bet they'll remember that for the rest of their lives.