Preliminary Study on Otolith Daily Increment Formation of Lake Salmon Opsaridium microlepis (Cyprinidae) Juveniles in Malawi

抄録

Features of sagitta, lapillus and asteriscus of laboratory-hatchedOpsaridium microlepis juveniles were investigated. The sagittae were arrow-head shaped, having obvious cores. Increments in the sagittae were observable until rostrum bases but invisible in rostrums. The lapilli were round fun-shaped, having obvious cores. Increments in the lapilli were observable from the core to the edge. Increments counts in the lapilli mostly agreed with actual age in days, indicating the lapillus being applicable for daily increments analysis. The asteriscus was oval-shaped, having ambiguous cores. Increment counts in the asteriscus were fewer than actual age, indicating the asteriscus being unsuitable for aging.