Impacts of magnetic water treatment on water quality, feeding efficiency and growth performance of common carp in integrated recirculating aquaculture systems

Abstract

An integrated recirculating aquaculture system (IRAS) is considered as an alternative solution for efficient utilization of available resources, nutrient recycling and maintaining ecological balance. The effects of using magnetized water on the growth performance of common carp (Cyprinus carpio L.) and water quality parameters were investigated in an IRAS. Six independent IRASs were designed; each system consisted of three tanks: a fish rearing tank, a waste-collection tank and a biological filter tank. An additional crop of macrophyte (Lemna minor) was used as a medium in the biological filter tanks in order to qualify as an IRAS. Two treatments with three replicates were set up in a randomized design. The experimental treatment was supplied with the magnetic field device, while there was no device in the control treatment. The fish growth, feeding efficiency and water quality parameters were measured in all systems. The results revealed that the use of magnetized water in the IRASs increased the specific growth rate of common carp and the growth rate of plants; while, decreased the feed conversion ratio. However, the magnetized water had no effects on the concentrations of ammonium nitrogen, nitrite nitrogen and nitrate nitrogen. The study suggested that the use of magnetized water in the IRASs could be beneficial as a cost-effective technique to increase the profitability of the system.