Morphological Development of Embryos and Juveniles in the Mozambique Tilapia, Oreochromis mossambicus as a Direct Developmental Fish under Rearing Conditions

Abstract

The Mozambique tilapia, Oreochromis mossambicus is one of the species introduced to Okinawa Island. This species breeds widely in the rivers of the island. In order to understand the biological aspects of O. mossambicus under the natural conditions of the island, a detailed observation of early morphological development was done under rearing conditions. The development of O. mossambicus was studied; it consisted of an embryonic phase of approximately 88 hours and 30 minutes, a free embryonic phase of about 12 days, followed by the juvenile period. The embryo became free-swimming on the sixth day of the free embryonic phase. The osteological development using enzyme-cleared specimens indicated that after reaching the juvenile stage, development of almost basic bones was complete 25 days after hatching.