(might contain spoiler)
You might have noticed that some fish is gone and new one has been added, also there is some that have their name changed from the previous game. Here's incomplete list from what I've noticed.
Gone: Bananafish, Goldbulb
New: Angelfish, Foxface
Changed: Fruitfish -> Tigerfish, Grouper -
> Pufferfish
Noticed something else to complete the list? Also, I'm just listing the families, so the fins good to go too.