Preheat oven to 250°F. Have a large sheet pan ready.
Melt butter in 7-10 second bursts in the microwave. When just a few slivers of butter remain, stop microwaving and stir until butter is completely melted.
Mix the Old Bay and MSG into the melted butter.
Pour Goldfish crackers into a large mixing bowl, then stir the melted Old Bay butter into the crackers until they are fully coated.
Pour the Goldfish onto the sheet pan and use a spatula or your hands to arrange them in an even layer so they don't stick together.
Bake for 20-40 minutes (or longer, if needed) until the Goldfish are dried throughout. Shake or stir the pan every 10-15 minutes as needed. Remove and let cool completely before eating.
Store in an airtight container.
RECIPE NOTES
This recipe makes 6.6 ounces of Old Bay Goldfish, which is 1 standard bag of Goldfish crackers.
To scale this recipe, the ratio is about 1½ tablespoons butter and 1½ teaspoons Old Bay per 2 ounces Goldfish crackers.
As long they have been completely dried throughout before you store them, they have about the same shelf life as regular Goldfish crackers. You don't want any trapped moisture when you store them!