Bostrychus is a genus of sleeper gobies in family Eleotridae, distributed widely across the Indo-Pacific - the atlas's two species draw records from Australia, China, India, Indonesia, Japan, Malaysia, Papua New Guinea, and Taiwan, tracking the estuaries, coastal rivers, and brackish lagoons where eleotrids thrive. Like other sleepers, Bostrychus species have an elongate, cylindrical body, a broad flattened head, and two separate dorsal fins, built as ambush predators that sit and wait on soft substrate rather than actively cruising the water column. Reaching 7.5–8.5 in, they are large by goby standards.
Neither species is a fixture of the aquarium trade - Bostrychus sinensis, the four-eyed sleeper, is better known as a food fish across parts of its East Asian range than as an ornamental one, and its size and predatory habits make it a poor fit for a community tank regardless. Bostrychus zonatus, the sunset gudgeon, sees occasional interest from brackish-water specialists drawn to its banded pattern, but sightings in the hobby stay uncommon. Both species are currently assessed Least Concern, consistent with a genus that ranges across a broad swath of Indo-Pacific coastal habitat rather than being confined to any one vulnerable system.