Opsarius signicaudus (Tejavej, 2012)

Family:  Danionidae (Danios), subfamily: Chedrinae
Max. size:  9.7 cm SL (male/unsexed)
Environment:  benthopelagic; freshwater
Distribution:  Asia: Khwae Noi and Khwae Yai branches of the Maeklong River, Thailand.
Diagnosis:  Distinguished from all congeners by the combination of the following characters: caudal fin- base with a large, elongated blotch (formed by the fusion of the large caudal spot at the fleshy end of the caudal base and the last vertical bar on the flank) that extends about 1/3 of the distance from the caudal-fin origin beyond the last scale on the caudal base to the margin of the caudal fork; anal-fin origin opposing the 2nd-4th branched dorsal-fin rays; eight scale rows above the lateral line; 36 or more precaudal lateral-line scales; dorsal fin with dark pigment concentrated mainly along the margins of the rays; small dentary tubercles; and, if present, a short, small pair of rostral barbels (Ref. 93076).
Biology:  Inhabits mountainous areas in fast-flowing streams and small rivers with clear water and gravel or cobble bottoms. Juveniles occur near shallow shorelines and behind large rocks where the flow is slower. Sympatric with Barilius koratensis, Poropuntius melanogrammus, Mystacoleucus marginatus, Garra spp., Rasbora cf. rasbora, Rasbora paucisqualis, Microdevario kubotai, Crossocheilus siamensis, Labiobarbus sp., Acanthocobitis zonalternans, Schistura spp., Nemacheilus pallidus, Botia morleti, Glyptothorax spp., Batasio tigrinus, Xenenthodon sp., Parambassis siamensis, Tetraodon sp. (Ref. 93076).
IUCN Red List Status: Not Evaluated (N.E.) Ref. (126983)
Threat to humans:  harmless

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