Bostrychus expatria

Bostrychus expatria is a small fish reaching a length of 14.4 centimetres (5.7 in). They appear as standard members of their family, with non-hydrodynamically-shaped bodies typical of bottom-dwelling fish. It possesses two completely separate dorsal fins, the first one supported by spines. The caudal fin is truncately-shaped, usually not much thicker than the peduncle itself. Its eyes are located dorsally, another trait commonly seen in benthic fish.

Bostrychus expatria has a single known population that can be found only in Lake Manguao in the Philippines. Lake Manguao is a freshwater lake located in the hilly areas in the northern part of the Philippine island of Palawan. The lake has at least four brooks draining into it, yet it has no rivers draining out from it. O. expatria shares the lake with at least two other endemic species of fish from the family Cyprinidae.

Owing to the remoteness of its habitat, there have been extremely few studies on this species. The few ones that have been done describe the fish as a benthic species, spending much of its time resting on the lake's bottom. Despite its size, B. expatria is predatory, known to feed mostly on the small crustaceans that make the lake's muddy bottom their home. It has also been known to ingest small fishes.

The species name, expatria was originally chosen by Herre to describe the fish as an expatriate. Bostrychus expatria was originally described by Herre as Boroda expatria. Boroda was derived from the Visayan word borod, which was used by the natives of the lake to refer to goby-like fishes. The name remained until 2021 when it was listed in the genus Bostrychus (as Bostrychus expatria) and so featured in Eschmeyer's Catalog of Fishes.

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