Two preservatives, formalin and alcohol as well as the freezing method were studied to show their effect on three morphological characters of two fish species of the family Mullidae (Mullus barbatus and M. surmuletus) collected from the Libyan coastal waters of the Mediterranean Sea near Benghazi City. The results showed a variable effect of the preservatives used and the freezing techniques. Shrinkage was the most common effect observed in the preservation tests, although a number of increase cases were obtained as well.