User blog comment:Kaido King of the Beasts/Chapter 863: Who's Afraid of the Big Bad Mom?/@comment-24850639-20170420151842/@comment-3507581-20170424010615

Didn't Luffy said earlier into the East Blue saga he'd have a crew compossed of 10 members -excluding himself-? So, going with the chapter-naming pattern when someone joins (check the list of chapters in this wiki), Jinbe would be "the Ninth".

Furthermore, to match Blackbeard and his "Ten Titanic Captains" should a battle between both crews happens, Luffy would need the same amount of people, right?