Oryzias sakaizumii Asai, Senou & Hosoya, 2012
Northern medaka
photo by Tibbatts, B.

Family:  Adrianichthyidae (Ricefishes), subfamily: Oryziinae
Max. size:  3.67 cm SL (male/unsexed)
Environment:  pelagic; freshwater
Distribution:  Asia: freshwaters along the Sea of Japan coast in the northern half of Honshu, from the Pacific coast of Momoishi, Aomori Pref. to Hyogo Pref. around Tango, Tajima district that distributional western limit is Hamasaka.
Diagnosis:  Oryzias sakaizumii is distinguished from all other congeners including O. latipes that are distributed throughout east Asia by the following combination of characters: distribution of melanophores, dense network of melanophores along each scale margin on the body surface in both sexes; depth of notch in membrane between dorsal-fin rays 5 and 6 less than half the length of rays in males; distinctive irregular black spots on the posterior portion of body lateral; and several silvery scales in patches on the posterior portion of the body (Ref. 89067).
Biology:  Occurs in ponds, marshes, and streams, such as irrigation canals amid paddy fields in flat alluvial lowlands. Well adapted to aquatic life on temporary floodplain wetlands (Ref. 89067).
IUCN Red List Status: Least Concern (LC); Date assessed: 01 March 2018 Ref. (124695)
Threat to humans:  harmless
Country info:   

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