Silver Pearlfish

The silver pearlfish, scientifically known as Encheliophis homei, is an eel-like species within the Carapidae family. This fish typically resides within the coelomic cavity of various sea cucumbers, including Bohadschia argus, Thelenota ananas, and Stichopus chloronotus, and is indigenous to the tropical and subtropical regions of the 🌊 Indo-Pacific Ocean.

Encheliophis homei is characterized by its slender, transparent body, which can reach a length of up to 19 cm (7.5 in). Its physical features include melanophores and silvery patches along the abdomen, a prominent swim bladder, a mobile upper jaw, small conical teeth, large eyes, and 116 to 128 vertebrae. The species exhibits an elongated dorsal fin with 33 to 38 soft rays and an anal fin with 53 to 61 soft rays. It also possesses pectoral fins but lacks pelvic fins.

In its adult stage, E. homei inhabits the body cavity of a sea cucumber, entering and exiting through the anus, and can occasionally be found in the respiratory tree or gut. Although limited information is available about its lifecycle, it is known to have a planktonic larval stage. Following this stage, the larva settles on the seabed in search of a sea cucumber host where it undergoes metamorphosis into a juvenile fish. Competition for host occupation is evident between Encheliophis homei and the closely related Carapus boraborensis, with juvenile E. homei sometimes found within the stomach contents of C. boraborensis, indicating aggressive interactions such as tail biting.

Once in open water, the fish does not necessarily return to its original host and exhibits no specific preference for the species of sea cucumber it inhabits. Prior to entry, it typically patrols the host's exterior, investigating it before nudging or tapping the area around the anus, usually entering head-first.

Initially, the silver pearlfish was considered parasitic. However, analysis of its stomach contents has revealed a diet consisting of amphipods, shrimp, and small fish, suggesting nocturnal foraging outside of its host.

The geographical distribution of the silver pearlfish encompasses the 🌊 Indo-Pacific Ocean, ranging from the 🌊 Red Sea and East African coast to the Society Islands (🇵🇫 French Polynesia), 🇹🇼 Taiwan, and northern and eastern 🇦🇺 Australia, likely extending to Tasmania. This species can be found at depths of up to 30 meters (98 ft).

The species is named in honor of Everard Home (1756-1832), an English surgeon and naturalist, who conducted collections along the 🇦🇺 Australian and Chinese coasts and may have collected the type specimen for this species.