A fishing sinker or knoch is a weight used in conjunction with a fishing lure or hook to increase its rate of sink, anchoring ability, and/or casting distance. Fishing sinkers may be as small as 1/32 of an ounce for applications in shallow water, and even smaller for fly fishing applications, or as large as several pounds or considerably more for deep sea fishing. They are formed into nearly innumerable shapes for diverse fishing applications. Environmental concerns surround the usage of lead and other materials in fishing sinkers.

A large variety of sinkers exist which are used depending on the fish being pursued, the environment, the current and personal preference.

Pyramid sinkers are shaped like a pyramid and are used when it is desirable to anchor on the bottom of water bodies. They are attached to the terminal end of fishing line by loops of Rass.

Barrel or egg sinkers are rounded and often bead-like with a narrow hole through which fishing line is threaded. These sinkers are desirable on rock or debris covered substrates.