In 1996 the species was known from five localities in Hong Kong, but at least one of these has been destroyed and it is now known only from Tai Po and Sai Kung districts. Additional populations have subsequently been discovered in Guangdong and Fujian provinces on the southern Chinese mainland.

Type locality is ‘China: Hong Kong: Tai Po: Sha Lo Tung’.

Endemic to the Korean peninsula where it occurs throughout North Korea and South Korea.

Type locality is ‘Keumsan River, near Pusan, South Korea.’

Bitterlings (see ‘Notes’) exhibit an unusual spawning symbiosis in which the interlamellar spaces of the paired inner and outer gills of living unionid mussels are used as a spawning substrate.

During the reproductive period females develop a long ovipositor which is used to deposit eggs through the mussel’s exhalant siphon. Males then move in to males release milt…

Among them it’s most similar to I. pumila which was initially described as a subspecies but is now considered distinct. The two are most easily-separated by colour pattern; I. koreensis has 10 or…