Seasonal Germ Cell Proliferation and Maturation Patterns in Indian Major Carp, Labeo Rohita (Hamilton, 1822) and Tilapia, Oreochromis Niloticus (Linnaeus, 1758)

The present work assessed the seasonal changes in germ cells (GC) and the maturation of rohu, Labeo rohita and tilapia, Oreochromis niloticus. Here, we showed two species representing two diverse types of spawning behavior, having two distinct GC proliferation and spawning patterns. During July, a single peak spawning season for rohu was recorded with the highest GSI (female: 19.5±1.29 and male 4.2±0.24), which is the peak monsoon time in Eastern India. However, two peak spawning seasons were marked in tilapia during the pre-monsoon (April) and post-monsoon (October) period with GSI values of male: 0.9±0.21, female: 3.9±1.32 and male: 1.1±0.3, female: 4.4±1.1 respectively. Gonadal histology in synchrony with GSI provides insights into the effects of various seasonal climate changes on the reproductive status of fish. Further, GC ultra-structure revealed various development stages in rohu and tilapia in different seasons using a scanning electron microscope. Here, comparative models were proposed for GC proliferation and maturation during different parts of the year in rohu and tilapia that may be used to plan breeding programs and hatchery management of these two species.