the effect of natural zeolite (clinoptiolite) on aquaponic production of red tilapia (oreochromis sp.) and lettuce (lactuca sativa var. longifolia), and improvement of water quality

the effects of natural zeolite as a bed medium in increasing lettuce and red tilapia growth as well as improvement of water quality parameters in an aquaponic system were investigated. an experiment with a completely randomized design was run with two treatments in triplicates, 1) an aquaponic system without use of zeolite as a control group and 2) use of a small cotton bag, containing 10 g zeolite as a bed medium for planting a lettuce seedling. in each experimental unit, 42 seedlings of lettuce were introduced. the individual weight of fish and lettuce yield in treatment 2 was significantly higher (p< 0.05) than treatment 1 at the end of experiment. the initial mean individual weight of red tila-pia juveniles was 6.23 ± 0.06 g and increased to 32.50 ± 2.00 and 37.50 ± 2.20 in treat-ments 1 and 2, respectively by the end of experiment. the yield of lettuce was higher in treatment 2 (1507 ± 445.00 g/unit) compared to the control (275 ± 83 g/unit). the concen-tration of total ammonia-n in the water was significantly lower (p< 0.05) in treatment 2 compared to treatment 1 at the end of experiment. the concentration of phosphorous and potassium in the fish rearing tanks was significantly lower (p< 0.05) in treatment 2. these results indicated that the use of zeolite, as a bed medium to plant lettuce seedlings in a re-circulating aquaponic system could increase the growth of lettuce seedlings as well as im-proving water quality parameters.