Effect of Acorus calamus and Curcuma zedoaria as a phytoremediation plant in Cyprinus carpio rearing tanks in a laboratory study

Abstract

Maintaining water quality in small-scale ornamental fish systems is challenging, making phytoremediation a sustainable, low-cost solution. This experiment evaluated the effect of Acorus calamus (Sweet Flag) and Curcuma zedoaria (White Turmeric) as phytoremediation plants in Koi carp rearing tanks over a six-week period. Three treatments were tested: C (control without plants), AC (tanks with A. calamus) and CZ (tanks with C. zedoaria), each with three replicates. Koi carp juveniles (30 days old; 2.35 ± 0.01 cm, 0.17 ± 0.00 g) were stocked at 10 fish/ tank (30 × 21 × 21 cm), and two plants were introduced into each respective tank. Fish growth performance was assessed using length, weight, growth parameters and survival, while plant performance was assessed based on height, wet and dry weight and leaf number. Water quality parameters were monitored throughout the experiment. After six weeks, the final length of koi carp in the CZ treatment (3.31 ± 0.29 cm) was significantly greater than in the AC (3.16 ± 0.19 cm) and control (3.03 ± 0.21 cm) groups. Fish in CZ (305.88 ± 5.88%) and AC (287.99 ± 17.65%) treatments exhibited significantly higher weight gain percentages compared to the control group. Plant performance was also superior in the CZ treatment, where the final height reached 50.18 ± 6.29 cm, significantly exceeding that observed in AC (33.45 ± 1.06 cm). The final root-to-shoot ratio was markedly lower in CZ (0.26 ± 0.09) than in AC (0.52 ± 0.12), indicating a differential biomass allocation. CZ tanks exhibited significantly improved water quality on day 42 with reduced ammonia (0.67 ± 0.05 mg/L), total hardness (26.69 ± 2.31 mg/L) and conductivity (99.50 ± 2.65 ms/cm). The study concludes that C. zedoaria performed better than A. calamus in maintaining water quality in Koi carp raring tanks.