:  The Pearlfishes
Taxonomy: Ophidiiformes, Pearlfishes  (Carapidae)
General Information: There are 7 genera and 32 species of pearlfishes. They all have elongate bodies and generally lack scales. They have an oddly-positioned anus and anal fin that are often directly below the pectoral fins.
Diet: These fish generally feed on food associated with their host, ranging from small invertebrates to small fish.
Final Note: The pearlfishes are rarely seen in the aquarium trade. Their occasional occurrence is usually due to their incidental capture with the collection of their host.

Examples at SeaScape Studio:
Silver Pearlfish