Wikipedia
Schismatogobius
Schismatogobius is a genus of fish in the goby family, Gobiidae. They are native to southern and eastern Asia, Australia and the Pacific Islands. Adults dwell in freshwater habitat such as streams and rivers, where they live along the sand and gravel substrates.
These fish are not always obvious in the habitat, because they are small and cryptic. They lack scales and have variable color patterns, with no two individuals of a given species alike. Compared to those of females, the jaws of males are "hugely large".