Water Quality Control And Suspended Particulate Matter Classification In Recirculating Aquaculture System For Two Difference Fish Culture

Recirculating aquaculture system(RAS) enable to control of high density breeding process and save water resources. Therefore, recirculating aquaculture model has become the dominate direction of the aquaculture industry. Due to the high density of breeding and feeding, the particles in the RAS would impact the water quality in the RAS. In order to removal of particulate matter effectively, it is necessary to classification the particulate mattes. In this study, the RAS in Dalian Tianzheng industrial Co. Ltd. was selected as the object, and the distribution of particulate matter in Tiger puffer(Takifugu rubripes) and half-smoothtongue sole(Cynoglossus semilaevis Gunther) breeding process in RAS was investigaed.Tiger puffer(Takifugu rubripes) is a promising species for aquaculture production because of its high value and limited supply. However, in the north of China, using sea cages to culturethis speciesin winter is hampered by the fact that the water temperature is extremely low. Here, a large scale commercial production of tiger puffer has been successfully realized using a recirculating aquaculture system from 3October 2012 to31 May 2013. The RAS combined with nine culture tanks(total water volume 200 m3) and stocked with approximately total 14400 fish(initial mean weight 160.0 g). The tiger puffer was hand-fed at a rate of 0.7% of total body weight per day, and the feed conversion rate was 1.2±0.3 kg/kg.The recycle water in RAS was treated by a sieve bend screen, a foam fractionator, a submerged biofilter, an UV sterilizer and a submersible aerator. During the whole culture period,an excellent water quality control was achieved in RAS. At the end of this experiment, the survival rate of tiger puffer was more than 98.0%.The final tank densities averaged 31.2 kg/m3, and the final individual mean weight of 440.0 g was obtained.The average concentration of suspended particles in Tiger puffer RAS was 0.0230 g/L, the organic suspended particles were 0.0193 g/L, particles size distribution was in 61-171 nm. After treatment of the system, the suspended particles average concentration were 0.0199 g/L, the organic suspended particle were 0.0155 g/L, the particles size distribution were in 90-110 nm. The suspended particulate matter were significant increased in 16:00 which is time feeding the fish, therefore a large number of suspended particles in the system comes from feeding.The average concentration of suspended particles in half-smoothtongue sole RAS were 0.0191 g/L, the organic suspended particles were 0.0162 g/L, particles size distribution were in 90-421 nm. After treatment of the system, the suspended particles average concentration were 0.0172 g/L, the organic suspended particle were 0.0145 g/L, the particles size distribution were in 90-110 nm. The suspended particulate matter were significant increased in 16:00 which is time feeding the fish, therefore a large number of suspended particles in the system comes from feeding.