Mahudu, Humphrey Matalu2020-12-142020-12-142015Mahudu, H. M (2015) Genetic variability among selected fish species along the Mwanza Gulf, Lake Victoria, Masters dissertation, University of Dar es Salaam, Dar es Salaam.http://41.86.178.5:8080/xmlui/handle/123456789/13817Available in print form, East Africana Collection, Dr.Wirbert Chagula Library, Class mark (THS EAF QL635.T34M33)The study utilized cytochrome b gene to investigate genetic diversity and variation among three populations of fish ; Oreochromis niloticus, Tilapia zillii and Lates niloticus collected from five different localities along the Mwanza Gulf i n Lake Victoria . DNA extraction was performed using Phenol­ chloroform protocol and sequenced to investigate genetic composition inter­ locality variation and inferring phylogenetic relationship. The result on genetic composition based on haplotype diversity, nucleotide diversity and n nucleotide difference showed high disparity i n genetic variation among 0. niloticus an d T zillii. The results on inter-locality showed that geographical distance has effect on genetic variation for T. zillii and 0. niloticus contrary to L. niloticus which showed less genetic variation between localities along the Gulf. Phylogenetic tree recon structured based on Maxi mum likelihood method showed monophyletic clade for L. niloticus with few segregation at Kishimba location. For O. niloticus and T. zilli formed paraphyletic group which indicate possibility of hybridization between O. niloticus and T. zillii. Lake Victoria being a potential source for aquaculture seeds. Management and conservation action should be taken to avoid loss of fish species in the lake.enFishesMwanza GulfLake VictoriaEnvironmental aspectsGenetic diversityThesis