Embryonic and larval development of Labeobarbus megastoma and Labeobarbus platydorsus(pisces: cyprinidae) in lake tana (Ethiopia)

Abstract

The information on the early ontogeny of the endemic Labeobarbus megastoma and Labeobarbus platydorsus fish species of Lake Tana are absent. In this paper we describe for the first time the full developmental sequence from egg to fingerling in controlled conditions. In addition, information on larval behavior, identification and developmental rates are provided. Embryonic development lasted 50:30h (26.3°C) and 61:38 (23.4°C) for the two species L. megastoma and L, platydorsus respectively and larval development to the morphology until the fry became very similar to the adult fish lasted 40 days (24.4°C). The mean total length of the newly hatched larvae of L. megastoma and L. platydorsus were 5.7±0.03 and 6.4±0.03mm respectively. The larvae hatched with closed mouth and anus, unpigmented eyes, large yolk and complete yolk absorption and exogenous feeding started on day 10 (8.9±0.07 and 10.5±0.12mm TL for L. megastoma and L. platydorsus respectively). The first posterior swim bladder aeration completed 5 days and 5 days and 6 h with 8.4±0.06 and 8.2±0.08mm TL for L. megastoma and L. platydorsus respectively and show full juvenile pigmentation and behaviour on the 41st day.