Heavy metal concentrations in fish pond water after application of EM-1® effective microorganisms

Effective microorganisms are being increasingly exploited in aquaculture. The aim of this study was to assess the effect of using effective microorganisms on heavy metal concentrations in fish pond water. This 105-day study was conducted at two fish ponds, control and experimental, used for commercial production of common carp (Cyprinus carpio). The EM-1® effective microorganisms were applied as a water supplement. The following elements were detected in the water of both fish ponds: aluminium, arsenic, beryllium, copper, lithium, manganese, vanadium, zinc, iron, barium, boron, uranium and strontium. Iron concentrations were highest in the fish ponds, ranging from 230.0 to 777.0 µg/L, whereas beryllium concentrations were lowest, ranging from the quantification limit to 2.5 µg/L. At the end of the study period, the levels of aluminium, beryllium, copper, manganese, vanadium, iron, barium, boron and uranium were significantly lower (P<0.05) and the levels of arsenic and strontium significantly higher (P<0.05) in the experimental fish pond as compared with the control fish pond, whereas the levels of lithium and zinc did not differ significantly (P>0.05) between the two fish ponds. Accordingly, the study results indicated the potential of EM-1® for improving fish pond water quality by reducing the concentrations of particular heavy metals in the water.