In the books, Victarion had 93 ships, but lost nearly half of them. By the time he reaches Meereen, he has 61 ships.
My hounds will never harm me.
Sansa Stark: You haven't fed them in seven days. You said it yourself.
Ramsay Bolton: They're loyal beasts.
Sansa Stark: They were. Now they're starving.
Ramsay Bolton: Sit. Down. Down!
Tyrion tells Daenerys about her father's diabolic plan to destroy King's Landing. There is no way Tyrion could know that, because Jaime has never told that to anyone except Brienne (Game of Thrones: Kissed by Fire (2013)).