Variability in cephalic morphometric and meristic characters of Oreochromis niloticus (Linnaeus, 1758) from three watercourses in Bunia (Ituri, D.R. Congo) and potential impact of some water abiotic factors
Paper Details
Variability in cephalic morphometric and meristic characters of Oreochromis niloticus (Linnaeus, 1758) from three watercourses in Bunia (Ituri, D.R. Congo) and potential impact of some water abiotic factors
Abstract
In fishes, some structures are of particular interest and can be influenced by some environmental factors. This study assessed the variability of cephalic morphometric and meristic parameters of Oreochromis niloticus in three rivers of Bunia (D.R. Congo) and the influence of some abiotic factors. A total of 780 specimens were sampled across nine stations. Eight morphometric and three branchial meristic characters of fishes were measured and their average values calculated. The head length varied from 2.94 to 3.75cm, head width from 1.24 to 2.33cm, pre-narial distance from 0.43 to 1.07cm, inter-narial distance from 0.49 to 1.08cm, snout length from 0.86 to 1.67cm, eye diameter from 0.82 to 1.10cm, interorbital distance from 0.83 to 1.46cm and post-orbital length from 1.33 to 194cm. The number of upper and lower gill rakers respectively, varied from 3.06 to 4.18 and from 19.41 to 23.69. Significant inter-river variations has been noted with some morphometric and meristic parameters (p<0.001). Water temperature ranged from 23.43 to 25.08 °C, concentrations of suspended solids from 193 to 461 mg/L, water turbidity from 3.10 to 23.56 NTU, pH values from 6.69 to 7.24, dissolved oxygen concentrations from 6.69 mg/L to 8.01 mg/L and the electrical conductivity ranged from 95.16 µS/cm to 210.87 µS/cm. Most cephalic morphometric were significantly correlated with the water turbidity, suspended solids and dissolved oxygen concentrations (p<0.001). Meristic parameters showed no significant relationships with physico-chemical parameters, confirming their stability. Phenotypic plasticity would constitute the primary mechanism of adjustment of O. niloticus populations to local environmental constraints.
Albertson RC, Kocher TD. 2006. Genetic and developmental basis of cichlid trophic diversity. Heredity 97(3), 211–221. DOI: 10.1038/sj.hdy.6800867
Binning SA, Chapman LJ, Cosgrove J. 2010b. The effects of hypoxia on the behaviour of Oreochromis niloticus and Tilapia zillii. Journal of Fish Biology 76(5), 1145–1158. DOI: 10.1111/j.1095-8649.2010.02559.x
Binning SA, Chapman LJ, Dumont J. 2010a. Feeding and breathing: Trait correlations in an African cichlid fish. Journal of Zoology 282(2), 140–149. DOI: 10.1111/j.1469-7998.2010.00725.x
Bitjanyom AR, Gilles A, Pariselle A, Snoeks J, Bilong CF. 2012. Allopatric and sympatric morphological divergence within Tilapia kottae. Cybium 36(2), 335–348. DOI: 10.26028/cybium/2012-362-003
Bitner MI, Smolina NV. 2026. Morphometry and fluctuating asymmetry of the gibel carp in bodies of water with different types of hydrology. International Journal of Aquatic Biology 14(1), 11–24. DOI: 10.22034/ijab.v14i1.2659
Burress ED, Martinez CM, Wainwright PC. 2020. Decoupled jaws promote trophic diversity in cichlid fishes. Evolution 74(5), 950–961. DOI: 10.1111/evo.13971
Chukwuka AV, Adebowale AH, Adekolurejo OA. 2019. Morphological differences and trophic niche breadth of Sarotherodon galilaeus and Oreochromis niloticus from the freshwater Lake Geriyo, North-Eastern Nigeria. Croatian Journal of Fisheries 77(1), 19–32. DOI: 10.2478/cjf-2019-0003
Conith AJ, Albertson RC. 2021. The cichlid oral and pharyngeal jaws are evolutionarily and genetically coupled. Nature Communications 12, 5992. DOI: 10.1038/s41467-021-26166-6
Decru E, Vranken N, Bragança P, Snoeks J, Van Steenberge M. 2020. Where ichthyofaunal provinces meet: The fish fauna of the Lake Edward system, East Africa. Journal of Fish Biology 96(5), 1186–1201. DOI: 10.1111/jfb.13992
Decru E, Vreven E, Snoeks J. 2017. The occurrence of an Eastern African haplochromine cichlid in the Ituri River (Aruwimi, Congo Basin): Adaptive divergence in an introduced species? Hydrobiologia 791(1), 209–220. DOI: 10.1007/s10750-016-2857-9
DeLorenzo L, DeBrock V, Carmona Baez A, Ciccotto PJ, Peterson EN, Stull C, Roberts NB, Roberts RB, Powder KE. 2022. Morphometric and genetic description of trophic adaptations in cichlid fishes. Biology 11(8), 1165. DOI: 10.3390/biology11081165
Depecker J, Asimonyio JA, Miteho R, Hatangi Y, Kambale J-L, Verleysen L, Stoffelen P, Janssens SB, Dhed’a B, Vandelook F, Honnay O. 2022. The association between rainforest disturbance and recovery, tree community composition, and community traits in the Yangambi area in the Democratic Republic of the Congo. Journal of Tropical Ecology 38(6), 355–367. DOI: 10.1017/S0266467422000347
Ekpo PB, Asuquo PE, Asukwo EN, Ekpo IP, Unoh FB, Etalong AI. 2025. Exploring the effects of seasonal shifts and climate variability on the physicochemical properties and morphological adaptations of Nile tilapia (Oreochromis niloticus) in the Great Kwa River, Nigeria: Implications for ecosystem resilience. Tropical Journal of Natural Product Research 9(7), 3328–3333. DOI: 10.26538/tjnpr/v9i7.61
Ghalambor CK, McKay JK, Carroll SP, Reznick DN. 2007. Adaptive versus non-adaptive phenotypic plasticity and the potential for contemporary adaptation in new environments. Functional Ecology 21(3), 394–407. DOI: 10.1111/j.1365-2435.2007.01283.x
Helfman GS, Collette BB, Facey DE, Bowen BW. 2009. The diversity of fishes: Biology, evolution, and ecology. 2nd ed. Wiley-Blackwell. DOI: 10.1002/9781444311907
Hess S, Prescott LJ, Hoey AS, McMahon SA, Wenger AS, Rummer JL. 2017. Species-specific impacts of suspended sediments on gill structure and function in coral reef fishes. Proceedings of the Royal Society B: Biological Sciences 284(1866), 20171279. DOI: 10.1098/rspb.2017.1279
Ibor OR, Eni G, Andem AB, Joseph A, Chukwuka AV. 2017. Sexual dimorphism in black jaw tilapia (Sarotherodon melanotheron) and banded jewelfish (Hemichromis fasciatus) from the Great Kwa River, Calabar, Nigeria. Croatian Journal of Fisheries 75(4), 122–131. DOI: 10.1515/cjf-2017-0016
Kalombo Kamutanda D. 2025. Territoires de la RD Congo. Cartographie des subdivisions. RDRMAPS Edit.
Kisezo PM, Katuala PB, Ndjogu AK. 2019. Évaluation des paramètres physico-chimiques et variations saisonnières des rivières Nyamukau, Ngezi et Shari à Bunia. Revue Congolaise des Sciences Nucléaires 8(1), 42–56.
Kwikiriza G, Yegon MJ, Byamugisha N, Nabwire R, Namulawa VT, Walakira JK, Rutaisire J, Muwanika VB. 2023. Morphometric variations of Nile tilapia (Oreochromis niloticus) local strains collected from different fish farms in Uganda. Fishes 8(4), 217. DOI: 10.3390/fishes8040217
Lamboj A, Snoeks J. 2000. Divandu albimarginatus, a new genus and species of cichlid (Teleostei: Cichlidae) from Congo and Gabon, Central Africa. Ichthyological Exploration of Freshwaters 11(4), 355–360.
Lamboj A. 2005. Nanochromis sabinae, a new cichlid species (Teleostei, Cichlidae) from the Upper Congo River area and northeast Gabon. Zootaxa 827, 1–11. DOI: 10.11646/zootaxa.827.1.1
Lévêque C, Paugy D. 2006. Les poissons des eaux continentales africaines: Diversité, écologie, utilisation par l’homme. IRD Éditions. https://horizon.documentation.ird.fr/exl-doc/pleins_textes/ed-06-08/010037336.pdf
Liem KF. 1974. Evolutionary strategies and morphological innovations: Cichlid pharyngeal jaws. Systematic Zoology 23(4), 425–441. DOI: 10.2307/2412485
Meier JI, Marques DA, Wagner CE, Seehausen O. 2022. The role of ecology in the evolution of cichlids from the African Great Lakes. Annual Review of Ecology, Evolution, and Systematics 53, 245–270. DOI: 10.1146/annurev-ecolsys-102220-014237
Mposo Nsangua B, Nshimba Nseya Wa Malale H, Katembo Wasingya É, Sabongo YP, Katembo Kasekete D, Mbuyu Mulongo L. 2025. Estimation du stock de carbone et potentiel de la biodiversité ligneuse à séquestrer le carbone en milieux urbains: Cas de la ville de Bunia en province de l’Ituri (RDC). African Journal of Empirical Research 6(4), 356–368. DOI: 10.51867/ajernet.6.4.31
Muschick M, Indermaur A, Salzburger W. 2018. Evolution: An archipelago replete with replicates. Current Biology 28(9), R565–R567. DOI: 10.1016/j.cub.2018.03.032
Ndiwa TC, Nyingi DW, Agnèse JF. 2016. Morphological variations of wild populations of Nile tilapia (Oreochromis niloticus) living in extreme environmental conditions in the Kenyan Rift Valley. Environmental Biology of Fishes 99(5–6), 473–484. DOI: 10.1007/s10641-016-0492-y
Olanrewaju AN, Nyaku RE, Kareem OK, Nasir A. 2026. Some aspects of population biology of Oreochromis niloticus (Linnaeus, 1758) from Lakes Alau and Bako, North-East Nigeria. Journal of Materials and Environmental Science 17(1), 47–58.
Omoniyi IT, Agbon AO. 2008. Morphometric variations in Sarotherodon melanotheron (Pisces: Cichlidae) from brackish and fresh water habitats in South-western Nigeria. West African Journal of Applied Ecology 12(1). DOI: 10.4314/wajae.v12i1.45767
Peel MC, Finlayson BL, McMahon TA. 2007. Updated world map of the Köppen–Geiger climate classification. Hydrology and Earth System Sciences 11(5), 1633–1644. DOI: 10.5194/hess-11-1633-2007
Popoola OM, Ebiwonjumi A. 2021. Assessment of morphological variations in wild populations of Nile tilapia from South West Nigeria. Agricultural Science and Technology 13(1), 70–75. DOI: 10.15547/ast.2021.01.013
Ronco F, Matschiner M, Böhne A, Boila A, Büscher HH, El Taher A, Indermaur A, Malinsky M, Ricci V, Kahmen A, Jentoft S, Salzburger W. 2021. Drivers and dynamics of a massive adaptive radiation in cichlid fishes. Nature 589(7840), 76–81. DOI: 10.1038/s41586-020-2930-4
Salzburger W. 2018. Understanding explosive diversification through cichlid fish genomics. Nature Reviews Genetics 19(11), 705–717. DOI: 10.1038/s41576-018-0043-5
Santos ME, Lopes JF, Kratochwil CF. 2023. East African cichlid fishes. EvoDevo 14(1), 1. DOI: 10.1186/s13227-023-00205-9
Schneider RF, Meyer A. 2017. How plasticity, genetic assimilation and cryptic genetic variation may contribute to adaptive radiations. Molecular Ecology 26(1), 330–350. DOI: 10.1111/mec.13880
Septya L, Wahid MR, Ilmi AN, Ulfa M, Rahmaniar R. 2025. Morphological variation of Anabas testudineus (Bloch, 1792) in Central Kalimantan: Insights into habitat-driven adaptations. Journal of Tropical Biodiversity and Biotechnology 10(4). DOI: 10.22146/jtbb.18398
Snoeks J, Vreven E. 2018. The ichthyofauna of the Congo Basin: Diversity, endemism and conservation. In: The Fishes of the Congo Basin, 11–38. Royal Museum for Central Africa, Tervuren, Belgium.
Stiassny MLJ, Schliewen UK. 2007. Congochromis, a new cichlid genus (Teleostei: Cichlidae) from Central Africa, with the description of a new species from the Upper Congo River, Democratic Republic of Congo. American Museum Novitates 3576, 1–16. DOI:10.1206/0003-0082(2007)3576[1:CANCGT]2.0.CO;2
Tiarks JH, Gray SM, Chapman LJ. 2024. Turbidity drives plasticity in the eyes and brains of an African cichlid. Journal of Experimental Biology 227(7), jeb246708. DOI: 10.1242/jeb.246708
Tougas S, Stiassny MLJ. 2014. Lamprologus markerti, a new lamprologine cichlid (Teleostei: Cichlidae) endemic to the lower Congo River in the Democratic Republic of Congo, west-central Africa. Zootaxa 3852(3), 391–400. DOI: 10.11646/zootaxa.3852.3.8
Tran-Ngoc KT, Dinh NT, Nguyen TH, Roem AJ, Schrama JW, Verreth JAJ. 2016. Interaction between dissolved oxygen concentration and diet composition on growth of Nile tilapia. Aquaculture 462, 101–108. DOI: 10.1016/j.aquaculture.2016.05.005
Van Steenberge M, Pariselle A, Huyse T, Volckaert FAM, Snoeks J, Vanhove MPM. 2015. Morphology, molecules, and monogenean parasites: An integrative approach to cichlid biodiversity. PLoS ONE 10(4), e0124474. DOI: 10.1371/journal.pone.0124474
Vranken N, Van Steenberge M, Snoeks J. 2019. Grasping ecological opportunities: Not one but five paedophagous species of Haplochromis (Teleostei: Cichlidae) in the Lake Edward system. Hydrobiologia 832, 105–134. DOI: 10.1007/s10750-018-3742-5
WWF (World Wide Fund for Nature). 2022. Congo Basin: Biodiversity and conservation. WWF. https://www.worldwildlife.org/places/congo-basin
Yoboue AN, Kouame KM, Boussou KC, Konan KF, Adepo-Gourene B. 2019. Morphological characterization of Mormyrus rume populations from Sassandra, Bandama and Comoé rivers in Côte d’Ivoire. International Journal of Fisheries and Aquatic Studies 7(5), 573–579.
Zogbaum L, Friend PG, Albertson RC. 2021. Plasticity and genetic basis of cichlid gill arch anatomy reveal novel roles for Hedgehog signaling. Molecular Ecology 30(3), 761–774. DOI: 10.1111/mec.15766
Jargy Kambale Soheranda, Nyongombe Utshudienyema Nathan, Moïse Nola*, 2026. Variability in cephalic morphometric and meristic characters of Oreochromis niloticus (Linnaeus, 1758) from three watercourses in Bunia (Ituri, D.R. Congo) and potential impact of some water abiotic factors. J. Biodiv. Environ. Sci., 29(2), 29-44.
Copyright © 2026 by the Authors. This article is an open access article and distributed under the terms and conditions of the Creative Commons Attribution 4.0 (CC BY 4.0) license.