Sleeper gobies are members of the
Eleotridae fish family, found predominantly in the tropical
Indo-Pacific, with about 35 genera and 182 species. While many eleotrids pass through a
planktonic stage in the sea and some spend their entire lives in the sea; as adults, the majority live in freshwater streams and
brackish waters. A few species (e.g.,
Milyeringa,
Typhleotris, and some
Bostrychus) are
troglobitic. They are especially important as predators in the freshwater stream ecosystems on oceanic islands such as
New Zealand and
Hawaii that otherwise lack the predatory fish families typical of nearby continents, such as
catfish.
Anatomically, they are similar to the
gobies (Gobiidae), though unlike the majority of gobies, they do not have a pelvic sucker.