Fish Biodiversity of the Indus River and Monthly Variations of Physico-chemical Parameters at Ghazi Ghat, Dera Ghazi Khan, Pakistan

Abstract

Fish communities are highly sensitive to fluctuations in aquatic environmental conditions; consequently, variations in physico-chemical parameters directly influence local fish diversity and abundance. The present study was conducted in natural lentic water bodies adjacent to the Indus River at Ghazi Ghat (30°3′48″ N, 70°48′51″ E), Dera Ghazi Khan, Pakistan. Physico-chemical parameters and fish diversity, including IUCN conservation status, were assessed monthly from March 2024 to February 2025 (excluding the closed season of June–August). A total of 23 fish species belonging to 18 genera and 11 families were recorded. Dominant species included Gudusia chapra (14.18 %), Oreochromis mossambicus (10.78 %), Labeo rohita (10.39 %), Securicula gora (10.11 %) and Catla catla (8.83 %). Family Cyprinidae contributed the largest share of species richness. Measured parameters (water temperature, light penetration, TDS, pH, dissolved oxygen, free CO₂, carbonate, bicarbonate, total alkalinity, total hardness, electrical conductivity, Ca²⁺, Mg²⁺, Na⁺ and Cl⁻) generally remained within ranges suitable for freshwater fish. Shannon–Wiener diversity (H′ = 2.73) and Margalef’s richness (d = 2.49) indicated moderate diversity. The findings confirm that the wetland habitats at Ghazi Ghat continue to support a commercially and ecologically important fish assemblage and underscore the need for continued monitoring and sustainable management.