Abdul Rahem Faqih, Maftuch, Seto Sugianto Prabowo Rahardjo, Cucun Herlina, Septi Anitasari, Asad Aulia Iqomuddin, Oktavia Herawati, Fatimah Sekar Alam, Cinca Hayyu Putri Satiti
Aquaculture plays a critical role in global and Indonesian food security, with the Nile tilapia (Oreochromis niloticus) being one of the most widely farmed species due to its rapid growth, adaptability, and high economic value. The Kekar strain, a locally improved Indonesian variety developed in East Java, has been promoted as a candidate for aquaculture expansion. This study aimed to integrate morphometric, meristic, and molecular analyses to evaluate the phenotypic variation, genetic diversity, and phylogenetic relationships of the Kekar strain tilapia. A total of 20 fish (10 males and 10 females, generation G015) were analyzed for morphometric and meristic traits, while seven individuals were subjected to mitochondrial cytochrome oxidase subunit I (coi) gene sequencing. Morphometric analysis revealed significant sexual dimorphism: males exhibited greater mean total length (42.20 cm) than females (40.94 cm), with significant differences in dorsal-fin base length (18.98 vs. 17.60 cm; p < 0.001), pre-ventral length (11.84 vs. 12.81 cm; p < 0.001), caudal-peduncle depth (5.74 vs. 5.19 cm; p < 0.001), and other characters, while meristic traits (dorsal XV–XVII; lateral-line scales 30–40) were largely conserved. The coi amplification produced ~655 bp fragments with 100% identity to O. niloticus reference sequences. Nucleotide composition was biased toward A+T (53.19%) compared to G+C (46.81%). Phylogenetic reconstruction clustered the Kekar strain tilapia within the O. niloticus clade alongside populations from Southeast Asia, India, Bangladesh, and China, supported by strong bootstrap values (100%). Genetic distance analysis revealed no divergence (0.0000) from other O. niloticus populations, while showing clear separation from O. mossambicus (0.0511) and O. aureus (0.0716). These findings demonstrate that the Kekar strain is phenotypically distinctive yet genetically homogeneous with global O. niloticus populations, while remaining differentiated from closely related species. The results provide a robust scientific basis for selective breeding and sustainable aquaculture development of this Indonesian local strain. © 2026, Egyptian Society for the Development of Fisheries and Human Health. All rights reserved.
Faculty of Fisheries and Marine Science, Universitas Brawijaya, Veteran Street, East Java, Malang, 65145, Indonesia; Aquatic Resources Management, Faculty of Fisheries and Marine Science, Universitas Brawijaya, Veteran Street, East Java, Malang, 65145, Indonesia; Master Programme Aquaculture, Faculty of Fisheries and Marine Science, Universitas Brawijaya, Veteran Street, East Java, Malang, 65145, Indonesia
