Variations in the reproductive performance of rohu Labeo rohita (Hamilton, 1822) under different agroclimatic zones of India

This study aimed to evaluate the induced breeding performance of the Indian major carp, rohu (Labeo rohita), in various agroclimatic zones of India. Breeding trials were conducted in 14 commercial hatcheries across four different Indian states: Andhra Pradesh, Tamil Nadu, Tripura and West Bengal. Except for Tamil Nadu, no significant variations in the breeding performance of rohu were observed. Breeding trials from Thanjavur District in Tamil Nadu showed a comparatively extended latency period, and lower fertilisation as well as hatching rates. The overall latency period was found to be more constant and lower (339±13 min) in temperatures between 24 and 31°C. Below 24 and above 31°C, a delay in spawning was observed. Fertilisation and hatching rates were optimal in the 24-30°C range, however at 31°C, these rates became inconsistent and began to decline. At 32°C, both fertilisation (~60%) and hatching (~50%) rates dropped significantly. Early season (pre-monsoon) breeding exhibited a significantly extended latency period (484.89±32.92 min), lower fertilisation rates (47-81%) and reduced broodstock response rates (≤75%). Despite these constraints, the hatching rates during the pre-monsoon period were significantly higher (93.13±3.09%) compared to monsoon breeding (86.77±6.02%). Keywords: Breeding, Fertilisation, Hatching, Indian major carp, Labeo rohita, Spawning, Temperature