Preliminary Study on Otolith Daily Increment Formation of Ntchila Labeo mesops (Picses: Cyprinidae) Juveniles in Malawi
2002 年 50 巻 3 号 p. 379-380
詳細
2002 年 50 巻 3 号 p. 379-380
Features of the sagitta, lapillus and asteriscus of laboratory-hatched and -reared Labeo mesops juveniles (56 days after hatching, 16.30-26.05mm TL) were investigated. The sagittae were arrowhead-shaped with obvious cores and fragile two rostra. Increments in the sagittae were observable until bases of rostra but were hardly visible in outer rostra. The lapilli were fan-shaped with obvious cores. Increments in the lapilli were well observable from the core to the margin. Increment counts in the lapilli did not significantly differ from actual age in days, indicating the lapillus being applicable for daily increments analysis until 56 days after hatching. The asterisci were oval-shaped with ambiguous cores. Increment counts in the asteriscus were fewer than actual age, showing the asteriscus being unsuitable for aging.
