Squamatological variations in five inland fishes of Bangladesh

Abstract

Fish scales have numerous hidden information in their structures that contribute in fish
identification and classification. In the present study, scales were collected and examined from twelve body
regions including lateral line of five fish species belonging to five Families and five Orders of inland fishes of
Bangladesh. A wide spectrum of variations in the scales of five fish was recorded concerning the surface
morphology, shape of the circuli, grooves, pattern of the different fields and the shape of ctenii. The
morphological descriptions were based on the scale’s type, shape, features of the anterior, posterior and
lateral fields, radii types, and circuli distribution. The microstructures included focus position and shape,
shape of first circuli, number of radii and tubercle size and shape. Results of the study reveals that scales of
the studied fishes were either cycloid or ctenoid types with notable variation in scale shape, circuli
distribution, focus position and shape, shape of first circuli, radii types and tubercle size and shape.
Considerable variation in lateral line scales were also observed and two types of lateral line scales observed
with three sub-types. Morphometric indices were calculated from scale of the anterior dorsal flank area of
each species and represented a valuable tool for species separation. The outcomes of the present study, first
of its kind in Bangladesh, would assist in resolving identification problems for future fish taxonomists and
fisheries-oriented researchers.