The answer to 'what is silverfish' is that silverfish are small, wingless insects that are grayish-silver in color and have a distinctive fish-like shape. They are nocturnal pests that thrive in moist, humid environments and feed on a variety of organic materials, including paper, fabric, and even dried foods.
Silverfish are typically between 12-19 millimeters (0.5-0.75 inches) in length and have a flattened, elongated body with three long, thin appendages at the rear. They move quickly and can be difficult to spot, often hiding in cracks, crevices, and other dark, secluded areas of the home.