MORPHOMETRIC ANSLYSIS AND REPRODUCTIVE SEASONALITY OF KINE MAGUR, Plotosus canius COLLECTED FROM THE SOUTH-EAST COAST OF BANGLADESH

Abstract

To unravel the mysteries of Plotosus canius, this study aims to elucidate the morphometric and reproductive behavior of this valuable fish species. Between March and September 2022, 42 eel tail catfish was collected from the southeast coast of Bangladesh. These specimens, comprising 19 males and 23 females, varied in size, with total lengths ranging from 242 to 788 millimeters and weights from 71.6 to 3291.6 grams. While females averaged 3.59 cm longer than males in this population, the size difference wasn't statistically significant (t-test, P > 0.05). Analyzing the body shape of P. canius using a network of 18 measurements across 12 key points revealed no difference between fish from two different areas. Both males and females of the grey eel catfish displayed a solid connection between their total length (TL) and pre-pectoral distance, as evidenced by the high regression coefficient of 0.979. Both sexes showed strong proportional growth (positive allometry). Males (W=0.0033TL3.1342) and females (W=0.0019TL3.2814) had similar LWR b-values (>3), with R² > 0.95. Body condition (Kn) varied little, averaging 0.146±0.038 for males and 1.456± 1.541 for females. Males mature earlier (33.4-35.3cm) than females (37.7-39.9cm) with a slightly female-biased sex ratio (1:1.2). Females of this species have significantly higher reproductive activity (GSI) compared to males, peaking in March. Histology of gonad shows that this species has a seasonal spawning (March-May), with distinct morphological changes in gonads marking maturity stages in both sexes. Fecundity, measured through the volumetric method was 2874 ± 794.62 eggs (diameter ~4.4±1.087 mm) per female. This study modeled P. canius growth, predicting a max length of 790mm at 4.16 years (Lt = 790{1-e-0.28(t+0.05)}). It provides the first data on the morphology of P. canius from Bangladesh coastal water, aiding sustainable management strategies.