Small pelagic clupeiform fishes play a crucial role in coastal fisheries and marine ecosystem functioning; however, species-specific growth information from the Gulf of Mannar remains limited. This study aimed to evaluate the length–weight relationship (LWR) and relative condition factor (Kn) of fourteen commercially important clupeiform fish species along the southeast coast of India. A total of 5,075 specimens were collected monthly from commercial fish landings at Thoothukudi and Pamban between February 2025 and January 2026. The LWR was estimated using the allometric model \(\:W=a{L}^{b}\) , and parameters including regression coefficient (b), intercept (a), coefficient of determination (R²), and relative condition factor (Kn) were calculated for each species. The growth exponent (b) ranged from 2.5019 in Stolephorus commersonnii to 3.1169 in Chirocentrus dorab. Eleven species showed negative allometric growth, while isometric growth was observed in Thrissina cuvierii and T. mystax, and positive allometry in C. dorab. New maximum length records were documented for Nematalosa nasus (28 cm) and Ilisha ditchela (18.5 cm). Additionally, this study provides the first estimate of LWR for Dussumieria hasseltii (b = 2.7701) from Indian marine waters, which was not previously documented in FishBase. Kn values were close to 1 for all species except S. indicus, indicating generally favourable growth conditions. These findings provide region-specific baseline data that are valuable for stock assessment and support ecosystem-based fisheries management in the Gulf of Mannar.
