This is a children's book aimed at two- to six-year-olds. The main character is a fish that goes on a journey in search of his family. On the way he meets different types of fish, who he befriends and they form their own unique family.
Wensum has a few close encounters; one with a human who is fishing and Wensum is caught, and the other with one of his fears, a giant pike known for eating other fish. But together they stay strong and reach his family.
I would say this book covers friendship, courage, ability, understanding and not judging others.