en Stock assessment Stock assessment پژوهشي Orginal research papers Present study emphasizing the population dynamics parameters of Gray eel catfish (<em>Plotosus canius</em>) that was scrutinized based on monthly length frequency data collected from mangrove estuary, Bangladesh from January 2017 to December 2018. A total amount of 1298 specimens was collected to estimate the total length (<em>TL</em>) and weight (<em>W</em>) of <em>P. canius</em> ranged from 13.3cm to 87.4cm and 28g to 5200g respectively. The length-weight relationship was<em> W</em><em>=0.006 L^2.</em>⁹⁵with<em> R²=</em>0.972 for both sexes. The von Bertalanffy growth function parameters were<em> L&infin;</em>=93.25cm and<em> K</em>=0.28yr^-1, hypothetical age at zero length of<em> t₀</em>=0.059 year and goodness of the fit of<em> R_n</em>=0.494. The growth performances indices for <em>L_&infin;</em> <em>and W_&infin;</em> were computed as<em> &Oslash;&#39;=</em>3.386<em> and &Oslash;=</em>1.84 respectively<em>.</em> The natural mortality was 0.51yr^-1 at average annual water surface temperature as 22^&deg;C. The total instantaneous mortality was 1.24yr^-1 at <em>CI_95%</em> of 1.05&ndash;1.42 (<em>r</em>²=0.986). While fishing mortality was 0.73yr^-1 and the current exploitation ratio as 0.59. The recruitment was continued throughout the year with one major peak during June-July was 17.20-17.96%. The Beverton-Holt yield per recruit model was analyzed by FiSAT-II, when <em>t_c</em> was at 1.443 yr, the<em> F_max</em> was estimated as 0.6yr^-1 and<em> F_0.1</em> was 0.33yr^-1. At the age of 0.6 year,<em> F_current</em> was 0.74yr^-1that is beyond the<em> F_0.1</em> that specified the current stock of<em> P. canius</em> of Bangladesh was over-exploited. Plotosus canius, Mangrove estuary, Asymptotic length, Growth, Mortality, Bangladesh 247 263 http://jifro.ir/browse.php?a_code=A-10-3694-2&slc_lang=en&sid=1 A.F. Rabby ahmed.bfri@gmail.com 100319475328460045495 100319475328460045495 Yes Bangladesh Fisheries Research Institute M.A. Haque ashrafbfri@gmail.com 100319475328460045496 100319475328460045496 No Bangladesh Fisheries Research Institute M.A. Islam amirulbfribs@yahoo.com 100319475328460045497 100319475328460045497 No Bangladesh Fisheries Research Institute, Riverine Sub-Station, Khepupara, Bangladesh S.J. Hasan ny_hasan80@yahoo.com 100319475328460045498 100319475328460045498 No Bangladesh Fisheries Research Institute M.A. Rahman Ahmed.sau31@yahoo.com 100319475328460045499 100319475328460045499 No Bangladesh Fisheries Research Institute, Riverine Station, Chandpur, Bangladesh Y. Mahmud 100319475328460045500 100319475328460045500 No Bangladesh Fisheries Research Institute, Mymensingh, Bangladesh