Creatures that may live inside oysters - hence the name

• Found living within the alimentary canals of e.g. sea cucumbers or between the shells of pearl oysters in or near shallow seagrass beds

Wiktionary Word definitions in Wiktionary
n. Any of various slender marine fish of the family ''(taxlink Carapidae family noshow=1)'', resembling eels.

Wikipedia Word definitions in Wikipedia
Pearlfish are marine fish in the Carapidae family of ray-finned fishes . Pearlfishes inhabit the tropical waters of the Atlantic , Indian , and Pacific Oceans at depths to , along oceanic shelves and slopes. They are slender, elongated fish with no scales, ...

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Pearlfish \Pearl"fish`\, n. (Zo["o]l.) Any fish whose scales yield a pearl-like pigment used in manufacturing artificial pearls, as the bleak, and whitebait.

WordNet Word definitions in WordNet
n. found living within the alimentary canals of e.g. sea cucumbers or between the shells of pearl oysters in or near shallow seagrass beds [syn: pearl-fish ]