Indian Flashlight Fish

The flashlight fish, Photoblepharon steinitzi, is a member of the anomalopid family within the order Beryciformes. This species is indigenous to the undefined and the 🌊 Red Sea, predominantly residing near coral reefs. As a nocturnal predator, the flashlight fish remains concealed within crevices and caves during daylight hours, emerging after dark to forage. Measuring up to 11 cm (4.3 inches) in length, it presents a compact and robust form.

The species is characterized by a primarily solid black body, accentuated by white markings around its pectoral fins and a lateral line of reflective scales. Significantly, it features bioluminescent organs beneath its eyes, aiding in prey detection, predator evasion, and intra-species communication. Reproduction among these fish is oviparous, a common trait within their order. Due to the lack of commercial value and its elusive, nocturnal behavior, current estimates of its population size and trends are not well documented.

Morphologically, the flashlight fish is recognizable by its dark, compact body, with its maximum length documented at 11 cm (4.3 inches) total length. It possesses a blunt snout and prominent eyes, typical of its family. Notable distinguishing features include a white splotch preceding the pectoral fins and, occasionally, a light discoloration spot at the top of its preopercle. This spot differentiates it from P. palpebratum, where the marking is more pronounced. A distinctive line of reflective scales runs laterally from the operculum to the caudal fins. Its bioluminescent organs, while appearing white, emit blue-green light in darkness. The flashlight fish also has the capability to cover these organs with black lids as needed.

Geographically, the flashlight fish is widely distributed across the undefined and the 🌊 Red Sea. With a latitudinal range extending from 21°S to 45°N, specimens have been collected from islands such as Réunion, Comoros, and as far east as the 🇲🇻 Maldives, extending north to 🇸🇴 Somalia, 🇴🇲 Oman, 🇮🇱 Israel, and 🇪🇬 Egypt. The typical environmental conditions of its habitat include water temperatures of approximately 26°C (79°F) and salinity levels around 35 PSU. The species occupies caves in coral reef areas at depths up to 500 meters (1,600 feet) during daylight, rising to 3–20 meters (9.8–65.6 feet) at night for feeding activities.

As a nocturnal predator, the flashlight fish employs various strategies for survival. It occupies caves and rock crevices by day and often shares these habitats with soldierfish (Myripristinae) and squirrelfish (Holocentrinae), while displaying territorial behaviors towards conspecifics. Solitary individuals or mated pairs defend their domain by swimming aggressively towards intruders and increasing the frequency of their light organ blinking. The species also uses its bioluminescent capabilities to evade predators through a "blink-and-run" tactic, misleading predators by swimming slowly in one direction with lights on before abruptly changing course and extinguishing the lights.

Human interaction with the flashlight fish is minimal due to its nocturnal lifestyle and lack of commercial interest. On occasion, local fishermen may utilize this species as bait. Previously categorized as Data Deficient by the International Union for Conservation of Nature (IUCN), its status was updated to Least Concern in 2020, reflecting its wide geographic distribution and the absence of significant threats to its existence.