| Family: |
Danionidae (Danios), subfamily: Rasborinae |
| Max. size: |
3.79 cm SL (male/unsexed) |
| Environment: |
benthopelagic; freshwater |
| Distribution: |
Asia: Alas River in northwestern Sumatra, Indonesia. |
| Diagnosis: |
Dorsal soft rays (total): 9-9; Anal soft rays: 7-7; Vertebrae: 31-32. Distinguished from all members of Rasbora trifasciata-group by a weakly developed post-opercular streak, which extends ventrally to the horizontal through the ventral margin of pupil (vs. distinct streak, which extends ventrally to reach the axillary lobe of pectoral fin). Can be further diagnosed from other members in northwestern Sumatra by the following combination of characters: male cephalic tubercles conical, distinctly pointed, with a shallow, wide depression basally; presence of cranial superficial neuromasts (each basal plate is lower than the skin surface and surrounded by peripheral ridge and groove, respectively); the first infraorbital (lachrymal) with a relatively straight dorsal margin, but without a posterodorsal process; the lachrymal region peripherally pigmented with an unpigmented central area; absence of dorsomedial branch of supraorbital canal toward posterior margin of frontal; an axial streak extending forward and terminating at the area between vertical through the dorsal-fin origin and the pelvic-fin insertion; the cephalic tubercles present only in males; a transverse scale count anterior to the dorsal-fin origin and pelvic-fin insertion of K4/1/2K; 12 circumpeduncular scales; an immaculate opercular flap; a basal reticulation pattern comprised of a network of well-developed parenthesis-shaped bars on the midlateral surface of the body; a maximum vertical coverage of the basal reticulation two and a half longitudinal scale rows; the lateral line absent from one to six posterior scales (only 20-26 scales perforated); lateral line series unpigmented on the posterior portion; and the pelvic-fin rays i,7 (Ref. 94947).
Description: Dorsal-fin rays ii, 7½; anal-fin rays ii, 5½; pectoral-fin rays i, 12-13; pelvic-fin rays i, 7; black basicaudal spot absent; gill rakers on 1st gill arch 12-13 (Ref. 94947). |
| Biology: |
This species mostly inhabits moderate-flowing turbid rivers. In streams with fast-flowing water, it tends to form school at the stream margins or the pool regions along the river banks. It occurs sympatrically with Rasbora api and R. cf. sumatrana (Ref. 94947). |
| IUCN Red List Status: |
Least Concern (LC); Date assessed: 27 December 2018 Ref. (130435)
|
| Threat to humans: |
harmless |
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