AM Mohammed, N Obadiah
This study was designed to assess and compare the phenotypic variability among the population of Nile Tilapia (Oreochromis niloticus) caught from rivers, Taraba and Donga. Sixty (60) Nile Tilapia (Oreochromis niloticus), 30 from Tella and 30 from Donga each, were purchased from artisanal fishermen in fish market monthly from July 2023 to October 2023. Descriptive statistics was used to compare the species from the two rivers, Taraba and Donga. The data obtained from the experiment were subjected to t-test at 95% confidence level (p=0.05) with the aid of IBM SPSS version 25. The results revealed significant size-related variation in the fish from the two different water environments. There is significant differences were observed in the 18 phenotypic parameters measured from the two water source and in all of the ten meristic counts recorded. A total of 94.4% and 83.3% of morphometric attribute of rivers, Taraba and Donga samples respectively are heterogenous (CV>10%) whereas a total of 80% of meristic attribute in river Taraba samples were heterogenous (CV>10%). It could be recommended for further studies to compare the morphological characteristics (such as slope, width, depth and sediment composition) of both rivers to identify similarities and differences in their geomorphology.