Pearlfish

[pɜ:lfɪʃ]

(noun.) found living within the alimentary canals of e.g. sea cucumbers or between the shells of pearl oysters in or near shallow seagrass beds.

Checker: Shari--From WordNet

(n.) Any fish whose scales yield a pearl-like pigment used in manufacturing artificial pearls, as the bleak, and whitebait.

Checked by Groves