Wikipedia
Luciogobius is a genus of fish in the goby family, Gobiidae. It is distributed along the coast of northeastern Asia, where species can be found in Korea, China, Taiwan, and Japan. Most species occur in Japan, and several are endemic.
These gobies are unusual in appearance and habitat preference. They are small fish, about 2 to 7 centimeters long, with very elongated bodies. The vertebral column is flexible and finely segmented, with many more vertebrae than most other fish in the family; they have up to 50 vertebrae, whereas most gobies have about 26. This extra-segmented spine helps Luciogobius species burrow in their common habitat, gravel beaches. Most vertebrates would have difficulty living in gravel that is constantly stirred by tidal action, but the flexibility of the bodies of Luciogobius is likely an adaptation to this environment. They also lack scales and the first dorsal fin.
Other habitat types occupied by species in the genus include estuaries, freshwater streams, and in the case of L. adapel, the seafloor up to 50 meters deep.
Most of the species studied spawn in the intertidal zone, but one species has been observed spawning in freshwater rivers. The eggs are generally attached to the undersides of rocks or are buried in the gravel or stone substrate.