Morphological status of the Mesopotamian spiny eel, Mastacembelus mastacembelus, populations from Karakay Reservoir, Tohma Stream and Tigris River were investigated using morphometric and meristic traits. Significant morphometric differences were detected among the populations, while meristic traits did not differ in three populations. Lower jaw length (LJL) was significantly smaller in Atatürk Reservoir population than the river populations of Tohma and Dicle. Stepwise discriminant analysis was applied for transformed morphometric and meristic data. In discriminant function analysis, morphometric differentiation was determined among the populations. The percentage of correctly classified individuals into their original groups was 71% for Tigris and Tohma and 97% for Karakaya populations. River populations had two more dorsal fin rays than reservoir. However, in the discriminant function analysis the populations were not clearly separated from each other in terms of meristic traits. The classification rates of meristic traits analysis were 86% for Karakaya and Tohma and 71% for Tigris populations.

Morphological status of the Mesopotamian spiny eel, Mastacembelus mastacembelus, populations from Karakay Reservoir, Tohma Stream and Tigris River were investigated using morphometric and meristic traits. Significant morphometric differences were detected among the populations, while meristic traits did not differ in three populations. Lower jaw length (LJL) was significantly smaller in Atatürk Reservoir population than the river populations of Tohma and Dicle. Stepwise discriminant analysis was applied for transformed morphometric and meristic data. In discriminant function analysis, morphometric differentiation was determined among the populations. The percentage of correctly classified individuals into their original groups was 71% for Tigris and Tohma and 97% for Karakaya populations. River populations had two more dorsal fin rays than reservoir. However, in the discriminant function analysis the populations were not clearly separated from each other in terms of meristic traits. The classification rates of meristic traits analysis were 86% for Karakaya and Tohma and 71% for Tigris populations.