Carapidae

Carapidae is a family of oviparous fish belonging to the order Ophidiiformes, commonly known as pearlfish or cusk-eels. These fish are characterized by their elongated, eel-like bodies, small eyes, and often translucent skin. Their fins are typically confluent, with the dorsal, caudal, and anal fins joined together. Carapids are found in tropical and subtropical waters worldwide, inhabiting marine environments from shallow coastal areas to the deep sea.

A notable characteristic of many carapid species is their symbiotic relationship with various invertebrates, particularly holothurians (sea cucumbers). Some species are known to live commensally within the cloaca of sea cucumbers, feeding on the host's gonads or other internal tissues without causing significant harm. Other species exhibit free-swimming lifestyles and are found in association with anemones, corals, or echinoderms. Their diet consists primarily of small invertebrates and fish. The reproduction of carapids involves external fertilization, and the larval stages are pelagic, drifting in the open ocean before settling into their adult habitats. The family includes several genera such as Carapus, Encheliophis, and Pyramodon.