Add the flour, grated butter, and cheese to a large bowl, mixing until combined. Transfer the cheese mixture to a food processor and pulse until you have coarse crumbs.
Pulse in the water 1 Tablespoon at a time until the dough forms a cohesive ball.
Mold the dough into a disc shape, wrap it up in plastic wrap, and chill for at least 20 minutes.
Preheat your oven to 350 degrees.
On a lightly floured surface or parchment paper, roll out your dough about ¼-⅛ inch thick.
Use your goldfish cutter to cut out as many goldfish as you can. Roll out the excess dough and cut some more until you've used it all.
Place crackers on a parchment-lined baking sheet.
Use a toothpick to make the eyes and mouth of the goldfish. Bake at 350°F degrees for 15-18 minutes until golden and crispy.
Notes
Store leftovers in an airtight container in the fridge for up to 3 days.
If you don't have a fish cookie cutter, you can simply cut the dough into small squares, kind of like Cheese-its.