Morphometric variations of twospot catfish (Mystus nigriceps) from Kampar Kanan, Kampar Kiri, and Tebo Batang Alai rivers, Indonesia

Twospot catfish, Mystus nigriceps, known locally as 'ingir-ingir' fish, is a popular consumption fish with high economic value. The exploitation of M. nigriceps continuously increases over time, which causes the declining of its wild population. Human interference is needed to maintain its existence, e.g. through domestication. Hence, more studies are essential for the conservation of this species, including on morphological aspects. This study aimed to assess the morphometric variations of M. nigriceps populations from Kampar Kanan (KKA), Kampar Kiri (KKI) and Tebo Batang Alai (TBA) rivers. 33 morphometric characters were measured using the Truss method on 150 individuals M. nigriceps evenly collected from the three rivers. Kruskal-Walls analysis revealed that 15 characters were significantly different. Further tests using Mann-Whitney showed that the most significant differences (18 characters) were found between the KKA and TBA populations, while the least significant differences (7 characters) were observed between the KKI and TBA populations. The cluster analysis with phenogram indicated that the differences in the morphometric characters among populations were in accordance with their geographical distance. The morphometric characters of the KKA population were more varied than those in KKI and TBA rivers.