As other reviewers have noted, this is about buying friendship, rather than sharing. Rainbowfish has to give his pretty scales away to other fish in order to stop them from shunning him (after one fish asks for a pretty scale, and Rainbowfish refuses - other fish then persuades remaining fish to shun Rainbowfish until he gives away his scales.). I note that teachers are encouraging of this book. Not a good reflection of the sort of morals taught in some schools, then. "It's good to shun people if they won't share their prized possessions" (body parts, in this case!), and "Buying friendship is perfectly acceptable".