Ultrasonographic sex determination of the flathead grey mullet (Mugil cephalus).

Overall, the sex determination of flathead grey mullet by ultrasonography was high in accuracy and speed, non-invasive and safe for fish and consumers, and may be considered a priority. Place of the organs in the M. cephalus coelomic cavity and the obtained experience showed that for rapid and easy sex identification, the best place to put the transducer is on the ventral surface of the fish in the caudal part of the coelomic cavity for taking transverse and sagittal ultrasonograms.