Age and growth of gangatic Mystus: Mystus cavasius (Hamilton-Buchanan, 1822) by length-frequency analysis from central Brahmaputra Valley, Assam

Abstract

The Gangatic catfish Mystus cavasius is a native catfish found in Brahmaputra and Barak valley of Assam which is a very popular food fish with has high market price. Our study provides the first data on age and growth of this species in central Brahmaputra valley of Assam. A total number of 285 specimens comprising of 103 males and 182 females have been studied using von Bertalanffy growth model and computer-based FiSAT programme was used for the estimation of growth parameters. In the FiSAT programme, the direct fit of length–frequency data such as Electronic Length Frequency Analysis-I (ELEFAN)-I technique, Shepherd’s method and Powell–Wetherall plot were employed in the present study. The Asymptotic length (L∞) and growth co-efficient (K) (annual) values of Mystus cavasius estimated by ELEFAN I, Shepherd’s method and Powell and Wetherall method. The value of L∞ and K by ELEFAN I, Shepherd’s method and Powell and Wetherall method are 217.0 mm and 0.8 year-1, 215.25 mm and 0.79 year-1 and 220.73 mm and 0.94 year-1 respectively. The two values of Mystus cavasius estimated about -0.41. The total length attained by this fish is about 135 mm at the end of 1st year, 180 mm at the end of 2nd years, 201 mm at the end of 3rd year and 210 mm at the end of 4th year.