Aquaculture is an increasingly important sector for food security and economic development in Afghanistan; however, limited data are available on water quality conditions and their relationship with fish health and productivity in local farming systems. This study evaluated the water quality of Qargha Fish Farm in Kabul, Afghanistan, and the biometric performance of cultured rainbow trout (Oncorhynchus mykiss). Monthly monitoring was conducted from spring to autumn at two sites: the reservoir inflow (Site 1) and the culture pond (Site 2). Key physicochemical parameters, including temperature, dissolved oxygen (DO), pH, total dissolved solids (TDS), ammonia, nitrite, nitrate, phosphate, sulfate, iron, and zinc, were measured both in situ and in the laboratory. Biometric data (weight, length, liver weight, and gonad weight) were collected from 60 fish to calculate condition factor (K), hepatosomatic index (HSI), and gonadosomatic index (GSI). Clear spatial and seasonal differences were observed. Site 2 showed lower temperature (mean decrease: 3.02 °C) and TDS, alongside substantially elevated ammonia (+ 110.8%) and zinc (+ 38.4%), suggesting associations between fish culture conditions and variations in water chemistry. DO concentrations were critically low in spring (3.24–3.30 mg/L), falling below optimal thresholds for trout. Correlation patterns among parameters (e.g., TDS–nitrite (at site 1 (r = 0,64) and site 2 (r = -0.81) and DO–iron (at site 1 (r = 0.36) and site 2 (r = -0.76) also varied markedly between sites. Biometric assessments revealed substantial seasonal growth, with a mean fish weight increase of 202.2% from April to December. HSI peaked in spring (May: 3.09%), suggesting heightened metabolic activity, whereas reproductive investment (GSI) remained modest and did not correspond to hepatic reserves. The length–weight relationship indicated positive allometric growth (b = 3.055). The observed associations between seasonal hypoxia, elevated ammonia concentrations, and nutrient-metal variability suggest conditions that may be physiologically challenging for trout, highlighting the importance of enhanced water quality monitoring and management in semi-intensive aquaculture systems such as Qargha Fish Farm. Not applicable.
Amin et al. (Thu,) studied this question.