Broodstock Maturation and, Effects of Ovatide Dose and Latency Periods on Reproductive Performance of Gangetic Mystus, Mystus cavasius (Hamilton, 1822)

Abstract

Mystus cavasius is commercially important because of its high market value in India and other South-East Asian countries. Various anthropogenic activities and natural habitat loss have placed this catfish on the near-threatened list. The development of captive spawning is an important approach for its conservation, aquaculture production, and consumer demand. Therefore, the present article describes the broodstock development and induced breeding of this small catfish. The optimal breeding period was determined based on the gonadosomatic index (GSI), whereas breeding performance and egg quality were evaluated based on spawning fecundity and the percentages of fertilisation and hatching, respectively. Monthly assessment of ovarian growth indicated that the highest (P < 0.05) GSI value was observed in July (18%), after which it gradually declined in subsequent months. Similarly, the optimal hormone dose and latency period were evaluated in two experiments. Twenty females (average body weight: 50 g) were stocked in four tanks and injected with Ovatide at 0.5, 1.0, 1.5, or 2.0 mL kg⁻¹ body weight, followed by stripping at 9 h. Females injected with 0.5 mL kg⁻¹ did not respond to stripping. Spawning fecundity was highest (P < 0.05) following injection with 2.0 mL kg⁻¹. The 1.0 mL kg⁻¹ dose produced significantly (P < 0.05) higher fertilisation (78%) and hatching (65%) rates than the other doses tested. A second trial using the 1.0 mL kg⁻¹ dose with latency periods of 9, 12, and 15 h showed no improvement in fertilisation or hatching percentages beyond 9 h. Optimal breeding performance and egg quality were achieved with 1.0 mL Ovatide kg⁻¹ body weight and a 9 h latency period. Thus, the present study establishes the optimal hormone-dose and latency-period combination for achieving the best breeding performance and egg quality of Mystus cavasius under captive breeding conditions.