The present study investigated the length–weight relationships (LWRs) and relative condition factors (Kn) of three penaeid shrimp species—Metapenaeus brevicornis, Metapenaeus affinis, and Mierspenaeopsis hardwickii, along the northwest coast of India. The samples were collected randomly once per month (January–December 2024) from commercial landings at Veraval, Jafrabad and Dholai centres along the northwest coast of India. A total of 2,251 specimens were sexed, measured for length and weight, and analysed for sex ratio (χ² test), LWRs (Le Cren 1951; W = a Lb, regression in R), growth pattern (t-test), and relative condition factor (Kn). In present study, annual sex ratios of all three species, M. brevicornis (1:1.06; χ² = 0.97, p > 0.05), M. affinis (1:0.94; χ² = 0.51, p > 0.05) and M. hardwickii (1:0.94; χ² = 0.76, p > 0.05) did not differ significantly from parity (1:1). The estimated b values ranged from 2.67 to 3.32, all within the expected biological range (2.5–3.5), indicating healthy growth. M. brevicornis exhibited negative allometric growth (b < 3), while M. affinis and M. hardwickii showed positive allometric growth (b > 3). The coefficient of determination (r²) values (0.92–0.97) indicated strong correlations between length and weight. The relative condition factor (Kn) for all species averaged near unity, signifying favourable growth conditions and ecological stability in the study area. This study provides the first global report of Kn for M. hardwickii and the first regional estimates for all three species. Results contribute essential baseline information for future comparative studies, stock assessment, and sustainable fisheries management of penaeid shrimp resources along the northwest coast of India.
