How clever is this

 How clever is this is a good title, well i think so.

A close friend recently found a book while out shopping that i may like. The book is all about Tropical fish, it.s called " The complete Encyclopedia of Tropical fish "

Great title it says it all Complete that's the word but it is wrong. Let me explain i have a 5,000 Lt tropical fish tank built into half a room in my cellar. The book is all about keeping, feeding and breeding tropical fish until you look close to the book cover.

Cover looks great but the mistake is the cover is for marine fish and no part of the contents has anything to do with marine fish. What a clever mistake to sell books however the book is still helpful to me.