Reproductive Biology of Ayre (Mystus aor) from the Kaptai Lake of Bangladesh: A Study to Brood Stock Improvement

Abstract

Life-history information is necessary for effective conservation, management, aquaculture development, and brood stock management of fishing populations, especially for fish with significant monetary exploitation. To characterize the life-history traits of long-whiskered catfish, Mystus aor from the Kaptai lake, Bangladesh, this research was conducted. Analysis of morphometric parameters revealed the exponent ‘b’ value of the length-weight relationship of M. aor to be 2.65 (negatively allometric) for the pooled data whereas 3.29 (positively allometric) for male and 2.4491 (negatively allometric) for female respectively. The monthly K values obtained ranged from 1.15 – 1.41 and the Kn value ranged from 0.14 – 0.25 and K was maximum during May (1.41 ± 0.57) and minimum during November (1.15 ± 0.05) whereas Kn value was maximum in July (1.07 ± 0.11) and minimum in the month of November (0.86 ± 0.16). Hepato-somatic index (HSI) values were highest at May (1.03 ± 0.26) and minimum in November (0.6 ± 0.12). Estimated relative fecundity ranged from 18474 − 55504 eggs/per fish. Oocyte diameter was found to be highest in May (0.83μm). Based on the gonado-somatic index, modified gonado-somatic index and Dobriyal Index, the length at first maturity (Lm) for M. aor female was 54.1cm and male was 49.5cm. Gonado-somatic index (GSI) values were highest at May for both male and female. Histological analysis also revealed the presence of yolk granules and a number of mature spermatids in April and May, respectively. Based on the findings of the study, it was concluded that April−May is the peak breeding season of M. aor. The findings of the current study will serve a baseline for the conservation management and brood stock development in the Kaptai lake of Bangladesh.