Recirculating Aquaculture Technology Of Cichlasoma Managuense

In recent years,with the rapid development of aquaculture in China,the traditional aquaculture mode had seriously polluted the water environment which caused serious harm to aquatic animals.Recirculating aquaculture system(RAS)is an advanced aquaculture production system developed in recent years.It has the advantages of environment controllable,high efficiency and water saving,and has been used in indoor production of a variety of fish.At present,there are few studies on recirculating aquaculture technology of Cichlasoma managuense.In this paper,the recirculating aquaculture system was designed,in which a 90 day feeding experiment of C.managuense was conducted.The growth performances of C.managuense and alterations of water quality in RAS were analyzed,and the removal effect of three-stage biofilter on aquaculture wastewater was explored,and the richness and diversity of microbial community in the three-stage biofilter were analyzed.The results are as follows:(1)To develop a system supporting rapid growth of C.managuens,a recirculating aquaculture system was designed and constructed based on the principle of substance balance.The system included rearing tank,microfiltration machine,submerged biofilter,ultraviolet sterilization pool,thermostat and oxygen supply machine.(2)The feeding experiment lasted for 90 d,the unit yield of the recirculating aquaculture system reached 35.33 ± 1.90 kg/m3,the weight gain and survival rate of C.managuens,were 24.50 ± 1.97 kg/m3 and 96.9± 0.1%,respectively;the mean value of ammonia nitrogen and nitrite in the aquaculture system were 0.953 ± 0.541 mg/L and 0.175 ± 0.089 mg/L,respectively;the contents of crude protein,crude fat,crude ash,water,essential amino acids and unsaturated fatty acids were 19.62 ± 0.20%,7.46 ±0.16%,1.05 ± 0.02%,70.88 ± 0.20%,6.59 ± 0.03 g/100g and 58.25± 0.13%,respectively,which were not significantly different from the control group(P>0.05).(3)The three-stage biofilters overall removal rates of total nitrogen,total phosphorus,ammonia nitrogen,nitrite and COD of the biological filter were 27.8%,18.5%,29.1%,62.4%and 14.4%;the first-stage biofilter average removal rates of total nitrogen,total phosphorus,ammonia nitrogen,nitrite and cod were 21.9%,16.9%,12.1%,17.9%and 14.4%;the second-stage biofilter average removal rates of total nitrogen,total phosphorus,ammonia nitrogen,nitrite and cod were 6.18%,11.9%,11.5%,20.9%and 1.73%;the three-stage biofilter average removal rates of total nitrogen,total phosphorus,ammonia nitrogen,nitrite and cod were 1.15%,1.91%,8.77%,45.8%and-0.04%;the removal efficiency of total nitrogen,total phosphorus,ammonia nitrogen and COD in the second and third stage biofilter was better than that in the first stage biofilter(P<0.05).(4)The average Shannon index were 5.086,5.050 and 5.147,Chao index were 1343.6,1254.3 and 1310.0.Nitrosomonas abundance were 0.28%,1.65%and 0.32%.Nitrospira abundance were 7.36%,5.40%and 10.0%,respectively;at the genus level,Nitrospira(4.2%-11.0%)was the dominant species,followed by SC-I-84_norank(0.4%～1 6.5%),Comamonadaceae_uncultured(1.6%～9.4%),Luteimonas(1.6%～6.2%))Micropepsaceae_uncultured(1.4%-4.1%),Microscillaceae_uncultured(2.0%～3.4%),Cetobacte rium(0.3%～5.1%),Rhizobiales Ineertae Sedis_uncultured(1.3%-4.1%),Flavihumibacter(1.1%～4.0%),env.OPS 17_norank(1.1%～2.7%),Schlesneria(0.1%～3.0%),Dongia(0.1%～4.8%),Kapabacteriales norank(0.2%～2.9%),Kineosporia(0.3%-4.1%),Thermomonas(0.4%～2.7%),Reyranella(0.3%～2.5%)Nitrosomonas(0.2%～1.9%).