Developmental morphology of the cyprinid fish Chela dadiburjori

Abstract

Embryonic, larval, and juvenile development of an Indian cyprinid fish, Chela dadiburjori, is described from laboratory-reared specimens. The eggs, measuring 0.7–0.9 mm in diameter, were demersal, almost spherical in shape, transparent and unpigmented, with a pale yellow yolk and no oil globule. Hatching occurred 50–61 h after fertilization at ca. 27°C. The newly hatched larvae, measuring 2.4–2.6 mm in body length (BL), had melanophores on the body with 14–16 + 14–17 = 29–31 myomeres. Two dark transverse bands on the ventral body surface and one melanophore on the lower margin of the eye in newly hatched larvae were diagnostic. Additionally, a cement organ for adhering to objects was present on the forehead of yolk sac larvae <3.1 mm BL. The yolk was completely absorbed at 3.5 mm BL. Notochord flexion was initiated at 5.0 mm BL and finished at 6.0 mm BL. Aggregate numbers of all fin rays were completed at 9.2 mm BL. Squamation was initiated on the caudal peduncle at 8.0 mm BL and completed at 10 mm BL. The eggs of C. dadiburjori resembled those of the closely related species Devario malabaricus and Danio rerio. The larvae and juveniles of C. dadiburjori were also similar to those of the latter species in general morphology, especially the presence of body melanophores in newly hatched individuals and a distinctive lateral streak on the head during the period from yolk sac to postflexion larvae. However, early yolk sac larvae of C. dadiburjori were more similar to those of Devario malabaricus than Danio rerio in having a cement organ on the forehead. Larvae and juveniles of C. dadiburjori differed from those of the latter two species in pigmentation on the ventral body surface at hatching and around the mouth during the period from preflexion to early postflexion larvae and in having a dark lateral streak or band on the body in postflexion larvae and juveniles.