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.
