Morphological differentiation between Bilih Fish (Cyprinidae: Mystacoleucus padangensis, Blekeer) in Singkarak Lake and Anai River, West Sumatra, Indonesia

Abstract

Mystacoleucus padangensis or bilih fish is an endemic species of Singkarak Lake. It has accidentally introduced to Anai River through water canal from Singkarak’s hydroelectric system. Changes in habitat type from lentic to lotic have been suppossed to force this species to make morphological adaptation. This study aimed to compare morphological variation of bilih fish living at the two habitat types. We measured 29 morphological characters of 400 individuals from each habitat. We also measured 19 environmental parameters. To clarify differentiation between the two population and environmental parameters we used mann-whitney U- test. The results showed differentiation between 13 characters of Anai bilih fish, i.e. preorbital distance, eye diameter, postorbital distance, head length, prepelvic distance, predorsal distance, head depth, body depth, caudal fork length, caudal peduncle length (ventral), anal fin base length, pelvic and pectoral fin length. The differences between some environmental parameters could take responsible to the differentiation of bilih. This study supports that adaptation to the water velocity has caused anterior differences between the two populations.