Scale surface topography of a vulnerable cyprinid fish, Schizothorax
plagiostomus from Kashmir Himalayas using Scanning Electron Microscopy
(SEM)
Abstract
Scanning electron microscopy (SEM) has significantly advanced
morphological studies, particularly in the investigation of fish scale
structures. This technique has unveiled intricate architectural details
that are crucial for fish identification and classification. In this
study, macro- and microscopic analyses were employed to examine the
scale morphology of Schizothorax plagiostomus, a vulnerable
cyprinid fish from Kashmir, focusing on two body regions (key scales,
which were taken from the region below dorsal fin and above lateral
line; lateral line scales which were taken from the lateral line). The
general scale type observed in Schizothorax plagiostomus was
cycloid. Two types of shapes viz., polygonal and cordate were reported
in this species. The rostral margin of the scales displayed round and
waved forms. The scales exhibited a small and round focus which was
antero-centrally positioned. The scales featured narrow or wide grooves
(radii) categorized into three types: primary, secondary, and tertiary,
present across all four scale fields (anterior, posterior, nuand
lateral), forming a tetra-sectioned type. Circuli, arranged in circular
patterns around focus were present which were densely placed in anterior
and lateral field and widely spaced in posterior field. Notably,
lepidonts on the circuli and chromatophores on the posterior margin were
absent in this species. These scale characteristics and their
morphologies offer a valuable tool for the identification,
classification, and phylogenetic analysis of various freshwater fish
species and genera.