Det verkar som om det inte förefaller ha ett annat namn än "Niffler" eller "The Niffler" (beroende på vilket perspektiv vi ser ifrån).
As Newt looks up toward Mary Lou, something seen from the corner of his eye catches his attention. The Niffler, a small, furry black cross between a mole and a duck-billed platypus, is sitting on the steps of the bank, hastily pulling the beggar’s hat full of money out of sight behind a pillar.
Fantastic Beasts and Where to Find Them: The Original Screenplay
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NEWT: [annoyed] Bugger — Niffler’s gone. Of course he has, little bugger. Any chance to get his hands on something shiny.
Fantastic Beasts and Where to Find Them: The Original Screenplay