Ontogeny and Growth of Early Life Stages of Barred Spiny Eel Macrognathus pancalus (Hamilton, 1822)

Abstract

Background: The objective of the study was to examine the growth and development of M. pancalus larvae in captive conditions, including pigmentation patterns, yolk and oil globule utilization, growth rates and metamorphosis, as well as to identify suitable live food for larviculture. Methods: The larvae, produced through induced breeding, were kept unfed until the yolk-sac absorption and then fed with freshwater rotifer, mixed zooplankton and Tubifex worms at different stages of development. The larvae were reared in indoor glass tanks and outdoor reinforced plastic tanks to document their morphological and chronological development. Result: The findings showed that the larvae exhibited typical characteristics of eel. Notably, dentition was observed before yolk resorption, indicating the highly predatory nature of the larvae. The bands of melanophores, which were prominent at the beginning, disappeared between 5-7 days post-hatch. Additionally, the study identified distinct features of spiny eels, such as a trunk-like rostral projection at 14 days post-hatch and erectile dorsal spines at 21 days post-hatch. The growth pattern, morphological changes and adaptation to benthic burrowing habits indicated that the larvae metamorphosed into the fry stage between 28-45 days post-hatch. These results provide valuable insights into the ontogenetic development and rearing of M. pancalus and can be used to support future aquaculture and conservation programs.