The term flashlight fish can either refer to:

• a family of fish, the Anomalopidae, also known as the lanterneye fish
• any one of a number of individual species, most but not all within that family, most commonly to the flashlight fish Photoblepharon steinitzi.

The family Anomalopidae is in the order Beryciformes, the sawbellies. There are some unrelated fish that show similar phenomena to those that get the Anomalopidae their name, and some of these are also called flashlight fish. Notable among these are the lanternfish, of the family Myctophidae in the order Myctophiformes, of which there are over 200 species.

The following species are in the family Anomalopidae:

• Splitfin flashlightfish, Anomalops katoptron, found in the warm waters of the western Pacific Ocean, sometimes in the very deep ocean trenches.
• Gulf flashlightfish, Phthanophaneron harveyi, found in the eastern Pacific Ocean and the Gulf of California
• Atlantic flashlightfish, Kryptophanaron alfredi, found in the Caribbean
• Parmops coruscans, found in the Eastern Pacific Ocean, and as far west as Tahiti and the Society Islands.
• Parmops echinatus, found in the Western Pacific Ocean, and as far east as Fiji.
• Eyelight fish Photoblepharon palpebratum
• Cook Islands flashlightfish, Protoblepharon rosenblatti, found near the Cook Islands
• Flashlight fish Photoblepharon steinitzi (sometimes regarded as a subspecies of P. palpebratusis), found in the Indian Ocean

Lanternfish sometimes known as flashlight fish include:

• Chubby flashlight fish Electrona risso, found in the eastern Atlantic Ocean and the Mediterranean Sea
• Spotted lantern fish Myctophum punctatum, found in deep waters of the Mediterranean Sea

The true flashlightfish, of the family Anomalopidae, have a luminous organ beneath the eyes; lanternfish have lights along its body. The light, which is red in colour and called bioluminescence, is generated by bacteria that live in special pouches. It is similar to the glow produced by fireflies.