FSH has a bunch of new fish at the XVI level, I believe, as said before. BTN ventures generally give me HQ apricots, HQ leeks, and HQ shroud tea leaves, but I have no idea if the earlier ventures could do that too. I've obtained three Littlefoot minions from BTN XVI ventures in under a week, so maybe those have a higher chance of getting the minions, but that's a very small sample size. OTOH, I've only ever obtained one Fat Cat, and it was from an XV FSH venture. XVIs have yet to bring me one.

I'm expecting the new XVI-only items to actually be added in 2.51 or 2.55. It wouldn't be the first time they added such new items to the latest ventures at a later date (see the Fat Cat and Littlefoot minions).