The Kyushu bitterling (''Rhodeus atremius'') is a

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

belonging to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Acheilognathidae, the bitterlings. It originates on

Kyushu Island is the third-largest island of Japan's four main islands and the most southerly of the four largest islands (i.e. excluding Okinawa and the other Ryukyu (''Nansei'') Islands). In the past, it has been known as , and . The historical regional ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

. It was originally described as ''Acanthorhodeus atremius'' by Jordan & Thompson in 1914. The fish reaches a size of up to , and is native to freshwater habitats with a pH of 6.8 to 7.8, a

hardness In materials science, hardness (antonym: softness) is a measure of the resistance to plastic deformation, such as an indentation (over an area) or a scratch (linear), induced mechanically either by Pressing (metalworking), pressing or abrasion ...

of 20 DH, and a temperature of . When spawning, the females deposit their eggs inside

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

s, where they hatch and the young remain until they can swim. There were two currently recognised subspecies, ''Rhodeus atremius atremius'' and ''R. a. suigensis'', but suigensis is now considered to be a separate valid species '' Rhodeus suigensis''.

References

Kyushu bitterling Kyushu region Kyushu bitterling Taxa named by David Starr Jordan {{Acheilognathinae-stub