Developmental morphology and growth in early stages of laboratory-reared Cirrhinus molitorella and C. microlepis (Cypriniformes: Cyprinidae)

Abstract

The morphological developments in laboratory-reared larval and juvenile Cirrhinus molitorella and larval C. microlepis were described, and ontogenies (including yolk sizes and absorptions, fin-ray and myomere numbers, allometric changes in the snout, upper jaw, head and pre-anal lengths, maximum body depth, eye diameter and melanophore distributions) were compared. Body lengths (BL) just after hatching were smaller in C. molitorella [3.3 ± 0.1 (mean ± SD) mm] than in C. microlepis (4.4 ± 0.1 mm), and subsequent increase in body lengths were slower in C. molitorella than in C. microlepis. Yolk sizes just after hatching were correspondingly smaller in C. molitorella than in C. microlepis and the yolks were completely absorbed by ca. 95 hours after hatching in the former and ca. 118 hours in the latter. In C. molitorella, fin-rays started appearing at a smaller size than in C. microlepis, with full complements attained by 14.4 mm BL (day 35) in the former, while they did not attain by 16.4 mm BL (day 20) in the latter. Allometric changes started in smaller sizes in C. molitorella than in C. microlepis. Total myomeres were 38–41 in C. molitorella and 39–43 in C. microlepis. Melanophore distributions progressed similarly in both species, except for a darker deposition on the caudal peduncle of C. molitorella of ca. 7–10 mm BL. Larvae of these species were identifiable mainly by differences in fin-ray numbers and allometries by size.