0
Article ? AI-assigned paper type based on the abstract. Classification may not be perfect — flag errors using the feedback button. Tier 2 ? Original research — experimental, observational, or case-control study. Direct primary evidence. Sign in to save

Influence of Physico-Chemical and Microbiological Water-Quality Variables on Aquaculture Species: A Vaal River Case Study (Gauteng, South Africa)

Asian Journal of Chemistry 2026
Landry S. Omalanga, Ednah K. Onyari

Summary

This review pulls together existing research showing that South Africa's Vaal River has concerning levels of pollution, including high salt content, heavy metals, and bacteria like E. coli, that are already causing fish die-offs and threaten the safety of fish farming in the area. Since fish from this river could end up on dinner tables, contamination with bacteria and metals matters directly for consumers, and the researchers stress that better water treatment and monitoring are needed to keep farmed fish safe to eat.

Study Type Environmental

This review examines the influence of physico-chemical and microbiological water‑quality variables on freshwater aquaculture in the Vaal river (Gauteng, South Africa). Available literature was examined to characterise key water‑quality parameters, including total dissolved solids (TDS), electrical conductivity (EC), turbidity, nutrients, heavy metals, microplastics, dissolved oxygen (DO), pH and microbial indicators such as Escherichia coli. In particular, this study discusses the interactive effects and aquaculture response in the Vaal river, links microbial dynamics to aquaculture health outcomes, gives the mechanistic interpretation of physico-chemical-biological linkages. The results showed the high TDS concentration (~177 mg/L) in the main stream of the Vaal river system is a potential threat to the agricultural sector, as it could be impacting on crop and aquacultural production and indications on DO concentrations are usually relatively high (>60%). The concentrations of metals in the Vaal river are generally high, leading to frequent fish kills. Furthermore, the high TDS concentrations in the Vaal river evidently influence the turbidity of the water and the higher pH values (6.3-8.7) in the Vaal river can be ascribed to higher algal concentrations. The high concentrations in E. coli (240 counts/100 mL) and algal pigments (69 mg/L) constitute a high risk the aquaculture production in the Vaal river system. To address these challenges, the water quality problem must be evaluated and resolved by reconsidering new management strategies and implementing treatment technologies. The findings of this work will assist relevant authorities in choosing appropriate water quality monitoring parameters for aquaculture areas.

Share this paper