The Adventures of Oliver the Clownfish: Invitation Slip-up

Invitation Slip-Up is the first book in the Oliver the Clownfish series. It is about a clownfish named Oliver who does not receive an invitation to his friend Sally the Seahorse's birthday party. Oliver goes through many emotions trying to figure out why he wasn't invited. Throughout the story he learns that miscommunications can occur between anyone, even good friends. He realizes that things are not always as they appear.