Study On Jade Perch(Scortum Barcoo)Cultured In Recirculating Aquaculture System And Biofloc-based Systems

Jade perch(Scortum barcoo)is a freshwater species which has been introducted in China successfully in 2001.It is considered to be a promising species.In aquaculture,feeding strategy is one of the main factors influencing the feed utilization and water environment.This experiment discusses the influence on the growth condition,feed conversion ratio,digestive enzyme activity and non-specific immunity ability of feeding rate and feeding frequency in a pilot scale recirculating aquaculture system.The results showed that the increase of feeding rate and specific growth rate increased with the increase of feeding rate,but there was no significant difference in digestive enzyme activity,too little or too much feeding could cause the increase of feed coefficient.The activity of superoxide dismutase(SOD)was significantly lower than that of the other two groups(P <0.05),while the other two groups(2% and 4% Significant differences.There were no significant differences among the other welfare indicators.In summary,it is suggested that about 60% of the high-quality fish should be cultured in the circulating water culture system.The feeding rate should be about 4%.The relationship between the weight gain rate and the specific growth rate and the feeding frequency was 4 times> 1 times> 2 times,and the feed coefficient decreased with the increase of feeding frequency.There was no significant difference in digestive enzyme activity between the two groups.The activity of lysozyme(LZM)in the experimental group was significantly higher than that in the experimental group(P <0.05).The difference between the experimental group and the other groups was not significant Fed the frequency of 1 times when the fish's immune capacity is stronger than 4 times the experimental group.There were no significant differences among the other welfare indicators.To sum up the recommendations in the circulating water culture system breeding high body leather,feeding frequency should be selected once a day.In order to compare the ability of recirculating aquaculture system(RAS)and biofloc-based systems(BFT)to deal with water quality and to promote the technology in more varieties of fish,this experiment was designed.The effects of RAS model(group A)and BFT model(group B)on water quality and growth status,digestion and other welfare indicators were compared.The results showed that the concentration of ammonia and nitrite in group A was increased rapidly and decreased at the initial stage(110.77±16.79)g and the average stocking density was 16.62 kg/m3 for 60 days.(P <0.05).The weight gain rate and specific growth rate of group A were significantly higher than those of group B(P <0.05).The water quality of group B was more stable than that of group B(P <0.05).There was no significant difference in the survival rate,terminal density,feed coefficient,liver body ratio and fatness of the two groups.Alanine aminotransferase(ALT)and aspartate aminotransferase(AST)activity were decreased in both groups.There was no significant difference in AKP activity between group A and group B.The activity SOD in group B was higher than that in group A,but the contents of TG and TC in group A were higher than those in group B.There was no significant difference in GLU content between two groups.TP contents in group A were lower than those in group B.The results showed that the water quality of the recirculating aquaculture system was more stable,and the growth rate of the high-body culture system was faster.In the BFT system,fish's non-specific immunity and nutritional status were better.The growth performance of meat or partial carnivorous fish in the bioflocculation system was not significantly improved compared to herbivorous fish.A 25-day experiment was designed to investigate whether the floc had an effect on the gills at high TSS and also to compare the effects of inorganic suspended particles(kaolin,sediment),non-bioactive organic suspended particles(feces)and biofloc on fish as well as to provide a theoretical basis for the promotion of BFT in the promotion of partial carnivorous fish.Group G,Group S,Group B and Group X were added solid suspensions of kaolin,sediment,feces and floc respectively,and the concentration reached 1000 mg / L.The experimental results show that the solid suspended solids formed by kaolin and sediment do not have the ability to reduce the concentration of ammonia nitrogen and nitrite in the whole experiment.The group which added fecal began to have significant ability to reduce the concentration of ammonia and nitrite during the fifth day of the experiment,although the C / N ratio was not deliberately controlled(without adding carbon source)during the experiment.There were no obvious rules for the welfare indicators of each group while the rules of survival rate is S group <G group <B group <X group.The histological examination of gill filaments showed that all kinds of suspended particles had a certain effect on fish gills under high TSS(1000 mg / L).Compared with other suspended particles,the biologically active flocs had less damage to the gills and followed by feces.Inorganic suspended particles(kaolin and sediment)on the gill of the largest damage.At the end of the experiment,gill epithelial cells shed,leading to increased mortality.