a fish
It is a fish.
Je vais te montrer comment attraper un poisson.
I'm going to show you how to catch a fish.
It isn't a fish.
Il sera heureux comme un poisson dans l'eau.
He’ll be as happy as a clam.
Tom a dit qu'il aimerait être un poisson.
Tom said that he would like to be a fish.
Tom a attrapé un poisson.
Tom caught a fish.