I needed some advice on what type of fish to buy for my new tank, so I bought two books that listed information on many different species. I looked up one particular species in both books and found that one book says this species grows to a length of up to 5 inches and the other book says it grows to a length of up to 14 inches. I thought there must have been a mistake here… Then I realised, one book was written by a woman and the other was written by a bloke.