Abstract
<title>Abstract</title> <p> The pelagic octopus genus <italic>Argonauta</italic> Linnaeus, 1758 is difficult to identify because high morphological variability of the female egg case, resulting in considerable ambiguity in species identification. Present study record seven female specimens landed as bycatch off Mumbai, on the north-west coast of India in the eastern Arabian Sea, during January 2025 (n = 5) and 26 February 2026 (n = 2). The species identification of muddy argonaut, <italic>Argonauta hians</italic> Lightfoot, 1786 was based on combination of diagnostic morphological character of a small, laterally compressed, smoky-brown shell bearing two rows of rounded keel tubercles and a broad aperture, together with a consistently elongated second arm pair which readily distinguishes <italic>A. hians</italic> from its only other Indian congener, <italic>A. argo</italic> Linnaeus, 1758. Dorsal Mantle Length (DML) ranged from 3.50 to 7.17 cm. The length–weight relationship (TW = 0.6715 DML^2.238) indicated negative allometric growth. The spawning, ripe and early-maturing females co-occurred, indicating protracted reproduction. The average fecundity varied from 5200This study confirms the occurrence of <italic>A. hians</italic> along the north-west coast of India and provides the first quantitative morphometric baseline and reproductive observations for the species from Indian waters. </p>