Length–weight relationships for 32 coastal fish species from the Mediterranean Marchica coastal lagoon, Nador (north-eastern Morocco) are presented in this study. Field studies were conducted during the period 2015–2016. The sampling gear used was a large seine net, targeting pelagic and demersal fish species. The most abundant families were Gobiidae, Labridae, Engraulidae, Atherinidae, Clupeidae and Sparidae. The fit of the equations (W=a L^b) with a and b parameters estimated from regular and functional regression (of log-transformed weight and length data) were determined. The exponent b varied between 2.1317 for Sparus aurata and 3.4897 for Pagellus acarne, whereas all the remaining values of b were higher than 2.91.