Effects of two hydroponic components on water quality, snakehead fish growth and leaf mustard production in aquaponic system

Aquaponic model is a farming system that integrates a recirculating aquaculture system with hydroponics. There are three hydroponic methods commonly employed in the aquaponics systems: the media bed (MB), the nutrient film technique (NFT) and the deep-water culture - floating rafts (DWC). This study was conducted to evaluate effects of two hydroponic systems (DWC and MB) on water quality parameters, growth rate of fish and development of vegetable in the aquaponic model of snakehead fish (Channa striata) and leaf mustard (Brassica juncea). Snakehead fish were stocked with a density of 40 fish/75 liters of water and were cultured for 167 days. The results showed that daily temperature, pH and dissolved oxygen parameters in the two systems were almost the same and relatively stable while the electrical conductivity in the MB was much higher than that in the DWC. Similarly, the levels of the parameters weekly monitored (ammonia, nitrite, nitrate, total phosphorus, and alkalinity) in the MB were higher than those in the DWC. At the end of the experiment, final weight, weight gain, specific growth rate and survival rate of fish in the MB treatment were higher than those in the DWC treatment, but the feed conversion rate of fish in the MB was lower than that in the DWC. On the contrary, vegetable yields in the DWC were significantly higher than those in the MB. In general, the DWC aquaponics work better than the MB system