Combined effects of salinity and potassium concentration on juvenile mulloway (Argyrosomus japonicus, Temminck and Schlegel) in inland saline groundwater

This paper reports on experiments conducted to examine the combined effects of salinity and potassium concentration on survival and growth of juvenile mulloway (Argyrosomus japonicus, Temminck and Schlegel) in inland saline groundwater. Three separate experiments were conducted in 20 (±1)°C water. In the first experiment, mulloway were held in 60 L aquaria (triplicate) with salinities of 5, 15, 25 or 35 g L^?1 and potassium concentrations of 20%, 40%, 60% or 80% of the concentration present in oceanic water of the equivalent salinity in a 4 × 4 factorial combination for 7 days. Response surface contour diagrams were generated from survival data to estimate optimal conditions. The results showed that maximum survival of juvenile mulloway occurred at salinities of >14 g L^?1 and potassium concentrations of >38%. Survival was lowest at salinities of <7 and >33 g L^?1 and potassium concentrations of <25%. The second experiment was conducted with mulloway held in 60 L aquaria at salinities of 15, 25 or 35 g L^?1 and potassium concentrations of 40%, 60%, 80% or 100% in a 3 × 4 factorial combination for 44 days. Optimal conditions for maximum survival and growth of mulloway were within a salinity range of 15–35 g L^?1 and potassium concentration above 40%. The third experiment was conducted in three 500 L tanks to record the survival and growth of mulloway fingerlings held at 20 (±1)°C, 23 g L^?1 salinity and potassium concentrations of 50% for 8 months. Survival and growth of mulloway fingerling in inland saline groundwater were similar to those reported from a semi‐intensive floating tank system in inland saline water and sea cage trials in oceanic water.