Evaluation of Fish Diversity and Water Quality in a Tropical Freshwater Ecosystem: A Case Study from Lakshmipuram Lake, Andhra Pradesh, India

Abstract

Freshwater fishes are one of the most threatened taxonomic groups that are due to degradation and defragmentation of habitats, introduction of exotic species, pollution, and global climate change. Lakshmipuram Lake, a tropical freshwater lake situated in India, plays a crucial role in maintaining ecological balance and sustaining local livelihoods. The present study investigates the ichthyofaunal diversity and water quality of Lakshmipuram Lake, located in the Anakapalli District of Andhra Pradesh, India, over a one-year period from January 2024 to December 2024. A total of 47 fish species were recorded from various sampling sites across the lake. Freshly collected specimens were cleansed, photographed, and preserved in 9–10% formalin solution, followed by identification through classical taxonomic techniques. The ichthyofauna comprised 12 different orders, among which Cypriniformes was the most dominant with 18 species (37%), followed by Siluriformes (10 species, 21%), Perciformes (3 species, 4%), and other minor orders such as Channiformes, Cichliformes, Anguilliformes (each 3 species, 6%), and so on. Regarding the population status, 11 species (23%) were categorised as abundant, 25 species (53%) as common, 4 species (8%) as moderate, and 7 species (14%) as rare. Based on the IUCN Red List (2024), 36 species (77%) were classified as Least Concern (LC), 8 species (16%) as Near Threatened (NT), 2 species (4%) as Not Evaluated (NE), and 1 species (2%) as Data Deficient (DD). In addition to biological assessment, 12 key physico-chemical parameters were analysed—including temperature, pH, dissolved oxygen, BOD, COD, turbidity, total dissolved solids, electrical conductivity, nitrate, phosphate, hardness, and alkalinity—to evaluate the water quality and its influence on fish diversity. Biodiversity indices were also calculated to quantify species diversity and distribution. The Species Richness was notable with 47 species, while the Shannon-Wiener Diversity Index averaged 2.765, indicating high species diversity. Pielou’s Evenness Index averaged 0.769, reflecting a high level of evenness in species distribution across sites. Lakshmipuram Lake is a biologically rich and ecologically important freshwater habitat, supporting a diverse and balanced fish community. The good water quality and high diversity indices emphasise the lake’s potential as a sustainable aquatic ecosystem.