Journal of Environmental Biology

Length-weight relationship, relative condition factor and reproductive parameters of Mystus cavasius (Hamilton, 1822) in the river Ganga

S.K. Ahirwal¹, A.K. Jaiswar², S. Bhushan², H.S. Mogalekar³, T. Kumar¹, J. Singh⁴ and K. Sarma¹*     

¹ICAR-Research Complex for Eastern Region, Patna-800 014, India

²ICAR-Central Institute of Fisheries Education, Mumbai-400 061, India

³Dr. Rajendra Prasad Central Agricultural University, Samastipur-848 125, India

⁴ICAR-National Bureau of Fish Genetic Resources, Lucknow-226 002, India

Received: 25 May 2024                   Revised: 04 July 2024                   Accepted: 04 October 2024

*Corresponding Author Email : kamalsarma67@yahoo.co.in                        *ORCiD: https://orcid.org/0000-0003-1982-7289

Abstract

Aim: In this study, length-weight relationship, relative condition factor, sex ratio, gonadosomatic index, and size at first maturity of Mystus cavasius were determined in the tropical river Ganga, India.

Methodology: Fish sampling was carried out monthly, and 562 specimens were collected from three landing sites of River Ganga. Total length and body weight were measured using a digital Vernier caliper (Insize-0/150) and digital weighing balance (Wensar MAB-220).

Results: In the length-weight relationship, the exponent values for male, female, and combined sexes are 2.8547, 2.8166, and 2.8569, respectively. The mean relative condition factor of male and female were 1.00±0.08 and 1.02±0.11, respectively. The overall sex ratio of the species is 1: 1.50, indicating predominance of female (Chi. Square value = 21.53, p<0.05). The species have a prolonged spawning season from June to October, peaking in August. Male reach maturity at 90.42 mm, while female reach at 100.21 mm.

Interpretation: In stock assessment studies, length-weight relationships provide useful information for estimating growth parameters, assessing population structure, developing yield equations, and comparing populations over time and space. Size at first maturity will be useful for setup of minimum legal mesh size of fishing gears to protect juvenile and recruitment overfishing for conservation of spawners and spawning biomass.

Key words: Catfish, Gonadosomatic index, Growth pattern, Mystus cavasius, River Ganga, Spawning season

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