循环水养殖罗非鱼氮收支及对水质影响的初步研究

Nitrogen budget and water quality of tilapia in recirculating aquaculture system

为提供实际生产理论依据,改良系统水处理工艺,开展循环水养殖系统中吉富罗非鱼氮收支和对水质情况的初步研究。起始养殖密度8 kg/m3,投饲率2%,系统循环量1 m3/h,总水量0.8 m3。试验期间溶解氧大于6 mg/L,pH 7.0～7.2,水温23～25℃。每周监测水质2～3次,监测指标包括氨氮、亚硝酸盐氮、硝酸盐氮,每2周检测1次水中总氮。用凯氏定氮法测定实验前后饲料、试验鱼体、粪便、悬浮颗粒的氮含量。结果显示,摄食氮有50.00±1.50%转化为生长氮,32.61±1.38%转化为排泄氮,17.39±4.0%转化为粪氮;58%的粪氮为悬浮颗粒物,42%为可沉淀颗粒物。

A preliminary study was conducted about nitrogen budget of tilapia in a recirculating aquaculture system to provide theoretical date for industrial production and improve the process of water treatment.Initial stocking density was 8 kg/m3,the feeding rate was 2% of fish body weight,the circulation volume was 1 m3/h and total water volume was 0.8m3.During the experiment,the dissolved oxygen was above 6 mg/L,the pH was 7.0-7.2,and water temperature was 23-25 ℃.Ammonia nitrogen,nitrite nitrogen and nitrate nitrogen was measured twice a week and total nitrogen was measured once a week.The nitrogen content of feed,fish,faeces and suspended particles was determined by Kjeldahl analyzer.Results showed that,the diet made（50.00±1.50）% growth nitrogen proportion,（32.61±1.38）% excretion nitrogen proportion and（17.39±4.0）% fecal nitrogen proportion.Additionally,about 58% of the fecal nitrogen was in the form of suspended solids nitrogen eventually.