This study investigates length–weight relationships of six clupeid species ( Alosa braschnikowi , Alosa caspia , Dussumieria acuta , Nematalosa nasus , Sardinella albella and Tenualosa ilisha ) captured from three main water bodies of Iran (Persian Gulf, Oman Sea and Caspian Sea), to evaluate if the LWR parameters fit for these fishes having specific morphological characteristics. Based on the obtained results, i) the b value was influenced by recorded length (TL, SL, FL) and body shape, ii) it was within the expected range of 2.27–3.48, iii) length–weight relationships were highly correlated and significant (r2>0.82-0.98, P <0.001), and hence length-weight equations fit well with six clupeid species in the Iranian water bodies. The results presented here, would be useful for fishery biologists and fisheries stake-holders in the study area