Study On Pond Juanyang Technology Of Siniperca Chuatsi

Mandarinfish（Siniperca chuatsi）is one kinds of famous freshwater fishes in China.It was popular for consumerrs because of the characteristics of high nutrional value and no intermuscular spines was popular for consumers.In recent years,pond culture is the most common way of freshwater aquaculture in China,which resulted a series of problems such as deterioration of water quality,fish disease,utilization of large amount of drugs,drug residues in fish and unstable quality of fish,limiting the healthy development of Mandarinfish industry.So promoting the transformation and upgrading of Mandarinfish culture mode is imminent.Juanyang system was suggested as a new intensive ecological green farming model with the advantages of energy saving,emission reduction,quality improvement and efficiency enhancement.In this paper,the feasibility of Juanyang of Mandarinfish was studied with the aim of providing technical support for the creation of an efficient and green culture model.The initial mean body mass and body length of the experimental Mandarin chuatsi were 48.25±13.27 g and 12.83±1.05 cm,respectively.Three density groups were set up:low density group（LSD）of 20 fish/m³（0.97 kg/m³）,medium density group（MSD）of 45 fish/m³（2.17 kg/m³）and high density group（HSD）of 70 fish/m³（3.38 kg/m³）.The main results of the study are as follows:The specific growth rate（SGR）and weight gain rate（WGR）of Mandarinfish decreased with increasing culture density in the first 90 days,of which the HSD was significantly lower than that of the LSD group（P<0.05）.From 91 to 210 d,the water temperature continued to decrease into the overwintering period,and SGR and WGR increased with increasing culture density,but there was no significant difference（P>0.05）.From 211 to 270 d,the total amount of bait fish put in was only about 20%of the total culture period,and there was no significant difference in SGR and WGR between densities（P>0.05）.Moreover,the survival rates（SR）of HSD,MSD and LSD groups were 69.02±5.57%,74.26±1.87%and 80.66±1.94%,respectively at the beginning of the culture period（0-30 d）,which were negatively correlated with the culture density.After30 days,the SR of all density groups was above 95%with no significant difference（P>0.05）.At the end of breeding,the yields of HSD,MSD and LSD groups were271.99±24.64 kg/circle,180.77±0.90 kg/circle and 85.14±3.45 kg/circle（13.60±1.23kg/m³,9.04±0.04 kg/m³,4.23±0.17 kg/m³）,respectively.The input-output ratios of HSD,MSD and LSD were calculated as 1:1.17,1:0.78 and 1:0.17,respectively,and the net profit per lap was 11144.35,5992.18 and 915.65 RMB.The crude protein content of each density group in Juanyang system was significantly higher than that of the pond control group,while the crude fat content was lower than that of the pond control group.Additionally,the contents of four presenting amino acids in Juanyang system,aspartic acid（Asp）,glutamic acid（Glu）,glycine（Gly）and alanine（Ala）,were significantly higher in the HSD and LSD groups than control ponds（P<0.05）.However,the essential amino acid index（EAAI）of the pond control group was significantly higher than that of the Juanyang groups at all densities（P<0.05）;In Juanyang system,the total amino acid content（TAA）and total essential amino acid content（TEAA）in the LSD group were significantly higher than those in the MSD and HSD groups（P<0.05）.The content of polyunsaturated fatty acids（PUFA）in Juanyang system was significantly higher than that of the pond control group,and the content of monounsaturated fatty acids（MUFA）was significantly lower,of which the content of docosahexaenoic acid（DHA）and eicosapentaenoic acid（EPA）in the pond control group was less than 1/2 and 4/5 of that in the pond test group.The GSM content was significantly lower in Juanyang system than in the pond control group（P<0.05）,which the GSM and 2-MIB contents were hardly detected,less than 1/35 of the olfactory quotient in each density group.During the whole culture cycle,the pond water quality was weakly alkaline,the water transparency was high,and the dissolved oxygen content in all density groups was above 5.0 mg/L.The concentrations of ammonia nitrogen（NH₄⁺-N）and nitrite（NO₂^--N）,which were toxic to Mandarinfish in all density groups,did not exceed 0.9 mg/L,and will not cause death of Mandarinfish.In addition,the stage of NH₄⁺-N and NO₂^--N concentrations increased sharply after feeding.In terms of water quality management,the daily discharge for 1 h could maintain the NH₄⁺-N and NO₂^--N concentrations in the bucket within the normal range without causing growth stress to Mandarinfish,and the discharge for 3 h could make the ammonia nitrogen and nitrite contents in the water of the pond inside and outside the pond（OP）consistent;the suitable replacement frequency of the bait fish escape control 10 mesh net was 15 d/time.To sum up,mandarinfish is suitable to be raised in Juanyang ponds when the bait is sufficient and the water temperature is appropriate.