Seasonal shifts in diet composition, stomach fullness, and trophic position of Synodontis serratus in Lake Nasser, Egypt

Khaled Y. AbouelFadl; Mahmoud A.H. Kassem; Manar Abdellatif; AbouBakr A.A. Elkady

doi:10.22034/ijab.v13i4.2569

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Khaled Y. AbouelFadl
khaledabouelfadl@aswu.edu.eg
Fisheries Department, Faculty of Fish and Fisheries Technology, Aswan University, Aswan, Egypt.
Mahmoud A.H. Kassem Fisheries Department, Faculty of Fish and Fisheries Technology, Aswan University, Aswan, Egypt.
Manar Abdellatif College of Marine Living Resource Sciences and Management, Shanghai Ocean University, Shanghai 201306, China.
AbouBakr A.A. Elkady Fisheries Department, Faculty of Fish and Fisheries Technology, Aswan University, Aswan, Egypt.

Vol. 13 No. 4 (2025): August

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August 25, 2025

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Analysis of Synodontis serratus' feeding habits is crucial to understanding its ecological role in Lake Nasser, Egypt. This study examined seasonal variation in stomach fullness in relation to diet composition and trophic level for S. serratus throughout the year, using 361 specimens collected from March 2023 to February 2024. The results from stomach content analysis indicated that S. serratus employed an omnivorous, opportunistic feeding strategy, characterized by significant consumption of benthic and pelagic organisms, including aquatic insects, diatoms, crustaceans, nematodes, mollusks, and protozoan zooplankton. There were also seasonal changes; the importance of zooplankton decreased during the summer, while both diet diversity and feeding activity diminished in winter. Stomach fullness reached its minimal levels during late winter and early spring before peaking after summer. The trophic level analysis showed that S. serratus mainly operates as a secondary consumer (mean trophic level 3.11), with peak values in March among smaller individuals. This is counterintuitive, given expectations regarding ontogenetic diet shifts and maturity, which would lead to increased resource-use efficiency due to body-size-scaled metabolic demand relative to food resource availability. These results underscore the adaptive dietary strategies exhibited by S. serratus and their prominent functional contribution to the food web, indicating that S. serratus is a key species for ecosystem resilience. This necessitates further exploration to guide fisheries management intervention strategies planned for Lake Nasser.

AbouelFadl, K. Y., Kassem, M. A., Abdellatif, M., & Elkady, A. A. (2025). Seasonal shifts in diet composition, stomach fullness, and trophic position of Synodontis serratus in Lake Nasser, Egypt. International Journal of Aquatic Biology, 13(4), 102–111. https://doi.org/10.22034/ijab.v13i4.2569

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Abdellatif M., Mohammed-Abdallah E., Abouelfadl K.Y., Osman A.G.M. (2021). Age and growth of Chrysichthys auratus ( Geoffroy 1809 ) ( Family?: Claroteidae ) from Lake Nasser , Egypt. The Egyptian Journal of Aquatic Research, 48: 417-424.

Adeyemi S.O. (2011). Food and feeding habits of Synodontis guttatus at Idah area of river. 10(2): 70-75.

Adeyemi S.O., Akombo P.M., Toluhi O.O. (2010). Food and feeding habits of Synodontis resupinatus. Animal Research International, 7(3): 1281-1286.

Admodisastro V.A., Baharuddin M., Madin J., Raehanah S., Shaleh M., Tan A., Hwai S., Ransangan J. (2023). Gut content analysis and selective feeding behavior of the asiatic hard clam Meretrix meretrix (Linnaeus, 1758) in Marudu Bay.Egyptian Journal of Aquatic Biology and Fisheries, 27(5): 939-957.

Allan J.D., Castillo M.M. (2007). Stream Ecology: structure and function of running waters. Springer. 450 p.

Aly W., El-far A., Karisa H.C., Nasr-alla A.M., Abouelfadl K.Y. (2018). Spatial and temporal variation of length-weight parameters and condition factors of commercial fish species in Lake Nasser, Egypt. 17th World Lake Conference, Lake Kasumigaura, Ibaraki, Japan, 2018At: Ibaraki, Japan.

Arame H., Adite A., Adjibade K.N., Imorou R.S., Stanislas S.P. (2021). Food habits, ecomorphological patterns and niche breadth of the squeaker, Synodontis schall (Pisces: Siluriformes: Mochokidae) from Niger River in Northern Benin. International Journal of Aquatic Biology, 9(1): 41-54.

Bachok Z. (2004). Diet composition and food habits of demersal and pelagic marine fishes from Terengganu waters, east coast of Peninsular, Malaysia. NAGA Worldfish Center Q, 27: 41-47.

Baker R., Buckland A., Sheaves M. (2013). Fish gut content analysis: Robust measures of diet composition. Fish and Fisheries 15(1): 1-8.

Begum M., Alam M.J., Islam M.A., Pal H.K. (2008). On the food and feeding habit of an estuarine catfish (Mystus gulio Hamilton) in the south-west coast of Bangladesh, University Journal of Zoology, Rajshahi University, 27: 91-94.

Briguglio M., Ram P., Abela G., Armelloni E.N., Papadopoulou N., Gaebel C., Hutton T., Abela G. (2025). What do people make of “Ecosystem Based Fisheries Management”? Frontiers in Marine Science, 12.

Elsaey S.E.F., Adam E., Abouelfadl K. (2024). Extension plan for bio-economic management of fisheries at Lake Nasser. Aquatic Science and Fish Resources (ASFR), 5(1): 43-56.

Fagbenro O.A., Adedire C.O., Owoseeni E.A., Ayotunde E.O. (2000). Food composition and digestive enzymes in the gut of Clarias gariepinus, Heterobranchus bidorsalis and their hybrids. Journal of Applied Ichthyology, 16(2): 94-97.

Friel J.P., Vigliotta T.R. (2006). Synodontis feeding ecology. Zootaxa, 1125: 45-56.

Gbaaondo T., Agba S., Igbana T.M., Tsevenda C.A. (2025). Food and feeding habit of some selected fish species from lower River Benue, Makurdi-Nigeria. Asian Journal of Research in Agriculture and Forestry, 11(1): 129-135.

Isumbisho M., Kaningini M, Descy J.P., Baras E. (2004). Seasonal and diel variations in diet of the young stages of the fish Limnothrissa miodon in Lake Kivu, Eastern Africa. Journal of Tropical Ecology, 20(1): 73-83.

Lévêque C., Paugy D. (2006). The fishes of African continental waters: Diversity, ecology and use by humans. IRD Éditions, Paris.

Mekkawy I.A., Hassan A.A. (2011). Some reproductive parameters of Synodontis schall (Bloch and Schneider, 1801) from the River Nile, Egypt. Journal of Fisheries and Aquatic Science, 6: 456-467.

Olowo U.C., Egun N.K., Oboh I.P. (2023). Some aspects of the reproductive biology of Synodontis schall from a lotic freshwater in Nigeria, 26(4): 256-267.

Pauly D., Palomares M. (2005). Fishing down marine food web: It is far more pervasive than we thought. Bulletin of Marine Science, 76: 197-211.

Pm A., Et A., So A. (2016). Diversity and abundance of Synodontis (Cuvier, 1816) species in the lower river Benue, Makurdi, Benue State, Nigeria. International Journal of Fisheries and Aquatic Studies, 4(1): 238-242.

Skelton P., Steven M.N. (1996). Book Review?: A Complete Guide to the Freshwater Fishes of Southern Africa. Copeia, 1996(3): 755.

Team R.C. (2024). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria.

Vagnon C., Rohr R.P., Bersier L., Cattanéo F., Guillard J., Frossard V. (2022). Combining food web theory and population dynamics to assess the impact of invasive species. Frontiers in Ecology and Evolution, 10.

Yongo E., Ojuok J.E. (2015). Diet composition and feeding habits of Synodontis victoriae in Lake Victoria, Kenya. African Journal of Ecology, 53(4): 496-505.

Yongo E., Iteba J., Agembe S. (2019). Review of food and feeding habits of some Synodontis fishes in African Freshwaters. Oceanography and Fisheries, 10(2): 1-5.