The present study investigates the length-weight relationship and the condition factor of populations of the Indo-Pacific fish Terapon jarbua (Forsskål, 1775) collected in the wider Gulf of Aden, notably from Socotra Island and the Hadramout coast of Yemen. This region displays a monsoon climate, with wide seasonal variation affecting estuarine habitats. A total of 620 specimens collected in estuaries and at sea were measured and weighted during field surveys carried out in 2007 and 2008 during pre- and post- South-Western monsoon periods. The length-weight relationship of the studied populations of Terapon jarbua is determined as W = 0.0288 × SL2.99, with r2 = 0.96 and is consistent with existing data on the species from other regions. Significant seasonal differences were found in Fulton's condition factor of Terapon jarbua.