I don’t know how to tell you this, but those aren’t big minions.
They don’t have any deathrattle or way to spawn additional minions, so the way to beat them is to trade 2/1 with only one of them and 1/1 with the rest and you win. All it takes is one cleave and you have them beaten.
Not to say it’s a given, but it’s not some impossible “omg this is so not fair!” build. It’s okay for murloc to win when it highrolls a really strong board, but people act like every time murloc is in the lobby they win first place walking away and that was never true.
Alternatively, Undead army will destroy 100/100 murlocs even with divine shield. When you’re spawhing +60 or more attack minions, over and over, boards melt pretty fast.