What is the origin of the idiom "fish in the pan" and when to use it?

The phrase "flash in the pan" originated from a type of gun, called a flintlock, in the 17th century. The gun had a small compartment that held a material that would ignite and create a flash of light when the gun was fired. However, sometimes this material would not ignite the main charge of the gun, resulting in no shot being fired. The metaphor of the flash of light without any real action can be applied to many situations where something looks impressive or successful but ultimately fails to achieve anything meaningful or lasting.