In this Tolarian Community College deck lecture video, The Professor invited Jonathan Zaczek, a.k.a. Nikachu to give us expert advice on how to pilot Merfolk and talk about why Merfolk is well-positioned in Modern after the recent unbannings of Jace, the Mindsculptor and Bloodbraid Elf. Nikachu also explains how Kumena Speaker (from Rivals of Ixalan) is pretty much the "Wild Nacatl of Merfolk" if played on Turn 1. Playing fish in Modern or Legacy is actually more complex than it seems. Nikachu's best advice here is not to treat it like an aggro deck (the biggest mistake Merfolk players make). There are tons of decision trees to consider and you should be able to play around your opponent's removal spells.
Watch the video below:
If you want to watch how the Master of Merfolk pilots his decks, you can watch Nikachu's Grand Prix Vancouver 2017 match with Josh Utter-Leyton's match below: