The current study aimed to conduct a biological evaluation of common carp (Cyprinus carpio) by comparing the length-weight relationship and the condition factor. The study also focused on morphological and meristic characteristics for river and cultivated common carp. The samples of the river fish were collected by the fishermen who were working at a beach called Al-Sahel located at the center of Abu Al-Khaseeb district, South of Basra Governorate, Iraq. Cultivated common carp in earthen ponds were brought from ponds farm of Aquaculture Unit-Agricultural Research Station of the College of Agriculture, University of Basra, Al-Hartha district, north of Basra. The common carp cultivated in floating cages were brought from floating cages farm located in Jurf Al Nasar district, north of Al- Mahaweel district, Babylon, Iraq. The results of the current study showed that the morphometric characteristics of the common carp are affected by the environmental factors present in specific areas. The morphometric characteristics (total length, forked length, standard length, head depth, head width, head and snout length) were found to be close within the range at the three environments. Significant differences were noticed between individuals of the three groups, with large differences in morphometric measurements. These results confirm that this method is a useful tool to differentiate between carp groups. There was a difference in the three sites that led to a change in some morphometric characteristics of the three groups. This difference may refer to a change in the environment or a change in the genetic composition or both or adaptation to living according to the abundance and quality and availability of food as in river fish. Based on results, each pair of barbels in fish was found to be close in length and number and was not affected by changes in the aquatic environment.