The Studies On The Application Of Biofilm-Biofloc Technique For Fish And Shrimp Intensive Aquaculture

The Biofilm Technique or Biofloc Technique,belonged to healthy aquaculture technology,has the effects of improving water quality and feed utilization,etc.,and was applied extensively.However,there were some problems,for example how to increase the effect of improving water quality and feed utilization for the Biofilm Technique,and how to control the appropriate biofloc density in water for the Biofloc Technique.On the base of the trial on the comparison between the Biofilm Technique and the Biofloc Technique,the Biofilm-Biofloc Technique was innovated in this research by integrating the two techniques.The application effects of Biofilm-Biofloc Technique used in Litopenaeus vannamei and Anguilla marmorata intensive aquaculture system were studied.The main reasults were as follows:?1?The contrast application of the Biofilm Technique and the Biofloc Technique for Anguilla marmorata factory aquacultureSix tanks were randomly divided into 3 groups,one group set biofilm purification water bar by 7.1%proportion of water as biofilm group,one group added composite carbon sources?sucrose:molasses:starch:feeding quantity=0.53:0.53:0.3:1?as biofloc group,another group of no treatment as control group.The results showed that the concentration of ammonia nitrogen,nitrite nitrogen,nitrate nitrogen content in biofilm and biofloc group were significantly lower than the control group?P<0.05?,and the ammonia nitrogen and active phosphorus removal efficiency of biofloc group is superior to the biofilm group,while the nitrite nitrogen,COD removal efficiency of biofilm group is better than the biofloc group;For the total bacteria and heterotrophic bacteria in water,the biofloc group was significantly higher than the biofilm group and the latter was significantly higher than the control group?P<0.05?.For vibrio quantity,the biofilm group was significantly lower than the control and biofloc group by 29.1%and 34.5%respectively?P<0.05?,and the proportions of the vibrio to the total bacteria of biofilm and biofloc group were significantly lower than the control group by 50.2%and 59.7%respectively?P<0.05?.Biofloc contains 46.6%crude protein and 9.1%crude fat in dry matter.During the trial,the water exchange rate of the biofilm group showed significantly lower than the control and biofloc group by 70.8%and 74.1%respectively?P<0.05?,and the eel survival rate was significantly higher than the control by 5.3%?P<0.05?.The eel survival rate and the growth rate of the biofloc group showed significantly higher than the control by 3.9%and 14.7%respectively?P<0.05?.?2?The optimization of conditions of Biofilm-Biofloc Technique application for juvenile Anguilla marmorata factory aquaculture.Using the L₉?3⁴?orthogonal experiment method to research the influence on different combinations of biofilm purification water bar?A1,A2,A3:0%,7.1%,10.6%?,sucrose?B1,B2,B3:0%,36%,53%?,starch?C1,C2 and C3:0%,20%,30%?and molasses?D1,D2,D3:0%,38%,53%?on biofilm-biofloc in Anguilla marmorata culture system.The results showed that:On the base of the best condition designed as follows:biofilm purification water bar set at the second level?7.1%?,sucrose and molasses set at the third level respectively?53%of the feeding amount perday?,starch set at the third level?30%of the feeding amount perday?,the Biofilm-Biofloc Technique would decrease the concentration of ammonia nitrogen and nitrite nitrogen in water quality,reduce the feed conversion ratio and enhanced the growth rate of Anguilla marmorata more effectively.?3?The effects on the application of Biofilm-Biofloc Technique for juvenile Anguilla marmorata factory aquaculture.Six tanks were randomly divided into three groups,two groups set biofilm purification water bar by 7.1%proportion of water,and added sucrose and starch respectively by 75%of the feeding amount perday as the treatment group?and?,another group of no treatment as the control group.The results showed that the concentration of ammonia nitrogen,nitrite nitrogen,nitrate nitrogen,total nitrogen,total phosphorus and solved reactive phosphorus in the treatment?were significantly lower than the control by 43.5%,38.3%,32.4%,22.4%,35.8%and 32.9%respectively?P<0.05?.The concentration of ammonia nitrogen,nitrite nitrogen,nitrate nitrogen,total nitrogen and total phosphorus in the treatment?were significantly lower than the control by 27.2%,51.7%,37.8%,33.3%and 20.4%respectively.The total bacteria and heterotrophic bacteria quantity in water of the treatments were 10⁷cfu/mL,which in the treatment?were highest and were significantly higher the control by 134%and 127%respectively?P<0.05?,vibrio quantity in the treatments were significantly lower than the control by more than 45%?P<0.05?.Biofloc contains crude protein more than 42%,while fat more than7%of the dry matter in the treatments.The water exchange rate and feed conversion ratio of the treatment?were significantly lower than the control by 48.9%and 12.6%respectively?P<0.05?,and the growth rate and specific growth rate were significantly higher than the control by 37.8%and 21.3%respectively?P<0.05?.The water exchange rate of the treatment?was significantly lower than the control by 57.4%?P<0.05?,and the growth rate was significantly higher than the control by 14.9%?P<0.05?.?4?The effects on the application of Biofilm-Biofloc Technique for Litopenaeus vannamei culture in earthern ponds.Six earthern ponds were randomly divided into two groups,one group set biofilm purification water bar and added sucrose by 30%of the feeding amount perday as the treatment group,another group set nothing as the control group.The results showed that the concentration of ammonia nitrogen,nitrite nitrogen,nitrate nitrogen,total nitrogen,solved reactive phosphorus and chemical oxygen demand?COD?in the treatment were significantly lower than the control by 39.8%,36.5%,36.4%,19.9%,21.6%and4.41%respectively?P<0.05?.The total bacteria and heterotrophic bacteria quantity in the treatment were significantly higher than the control by 47.5%and 77.3%respectively?P<0.05?.The algae density and cyanobacteria relative density in the treatment were significantly lower than the control by 51.3%and 31.6%respectively?P<0.05?,and the diatom relative density was significantly higher than the control by 44.4%?P<0.05?.The biofilm-biofloc has high nutritional value,with 85.0%moisture,40.6%crude protein and 6.5%crude fat in dry matter on average.The shrimp survival rate,harvest size and yield in the treatment were significantly higher than the control by 32.6%,18.3%and 56.9%respectively?P<0.05?,and feed conversion ratio was significantly lower than the control by 26.1%?P<0.05?.To sum up,although the application of Biofilm Technique or Biofloc Technique has the effects of improving water quality and improving feed efficiency,the Biofilm-Biofloc Technique was innovated in this research by integrating the two techniques,which improved water quality better,effectively controled deposition of biofloc in water,improved micro ecological environment in water body,reduced the feed conversion ratio and increased the growth rate of fish and shrimp cultured.Therefore,the Biofilm-Biofloc Technique would have more broad application prospects.