OK, I opened it for you...
pg 148...
The cleaner wrasse is a popular fish in the marine aquarium and is well suited for the beginner. blah, blah blah...
and ends with,
"More than one cleaner can be kept in the same tank as well".
Not all books will have 100% accuracy, but since this was the first thing I read, and even as a new hobbiest, I knew better, so the book lacks merit IMO.