奥尼罗非鱼当年苗种池塘养殖达出口规格试验

在广西水产研究所那马中试基地进行了池塘养殖当年繁殖的奥尼罗非鱼苗种达出口规格试验。在1800m^2池塘中投放全长为3—4cm的奥尼罗非鱼鱼苗2860尾，经178d养殖，奥尼罗非鱼平均体重为O．75kg/尾(最大为1．1kg／尾)，平均体长为26．1cm(最大为29．5cm)，总产量为1750kg，平均产量为648kg／667m^2，养殖成活率为81．6％。     

山涧水流水养殖黑脊倒剌鲃试验

利用山涧水开展流水养殖黑脊倒剌鲃,在128m2水泥池中放养规格为10-11尾/kg的鱼种1042kg(10560尾),养殖密度82尾/m2.经271d养殖,收获平均体重511g的倒剌鲃商品鱼5039kg,净产量3997kg;饵料系数2.58,养殖成活率93.34%,净单产31.24kg/m2,利润119.05元/m2,投入产出比为1∶1.78,取得较好的经济效益.     

吉奥罗非鱼养殖试验

本文通过进行吉奥罗非鱼养殖试验，探讨和验证吉奥罗非鱼所的优良经济性状，并获得了显著的效果。在21．45hm^2的池塘中投放平均体重60g的吉奥罗非鱼鱼种48800尾，经192d养殖，吉奥罗非鱼平均体重为0．948kg/尾（最大体重为1．201kg／尾），吉奥罗非鱼产量为44．98t，平均产量为31．02t／hm^2总产值为32．4万元，获利7．65万元，经济效益显著。试验表明，吉奥罗非鱼集成了吉富罗非鱼生长速度快，奥尼罗非鱼雄性率高、抗病力强等优点，适合于不同地区、不同环境的池塘养殖，推广养殖前景广阔。     

大规格优质奥尼罗非鱼养殖试验

在2.13 hm2的池塘中投放平均体质量370 g的奥尼罗非鱼鱼种34 000尾,经124 d养殖,奥尼罗非鱼平均1.12 kg/尾,最大为1.81 g/尾,平均体长29.3 cm,最大为35.5 cm。奥尼罗非鱼产量38 050 kg,总产值30.9万元,获利9.1万元,经济效益显著。选用良种是基础,投喂优质饲料是关键。     

吉奥罗非鱼养殖试验

文章通过吉奥罗非鱼养殖试验，探讨和验证吉奥罗非鱼的优良经济性状，并获得了显著的效果。在21.45hm^2的池塘中投放平均体重60g的吉奥罗非鱼鱼种48800尾，经192d养殖，吉奥罗非鱼平均体重为0948kg/尾，产量为44．97t，平均产量为31．06t／hm^2，总产值为32．4万元，获利7,65万元，经济效益显著。试验表明，吉奥罗非鱼集成了吉富罗非鱼生长速度快，奥尼罗非鱼雄性率高、抗病力强等优点，适合于不同地区、不同环境的池塘养殖，推广养殖前景广阔.     

罗氏沼虾、尼罗罗非鱼单养或混养的试验比较

将罗氏沼虾、尼罗罗非鱼单养与混养进行了生长比较，每种养殖方式设3个重要。单养罗氏沼尾虾放养密度为7只/m^2，单养尼罗罗非鱼放养密度1尾/m^2。混养密度为罗氏沼虾7只/m^2和罗非鱼1尾/m^2。罗氏沼虾放养规格为1～1.3g/尾，尼罗罗非鱼放养规格7～8g/尾，养殖5个月捕获。结果表明：罗非鱼单养和混养产量与平均个体重无显著性差异，总产量分别为2952kg/hm^2和2779kg/hm^2，平均个体重分别为350g/尾和334g/尾。罗氏沼虾单养与混养产量分别为1377kg/hm^2和961kg/hm^2，平均个体重分别为56g/只和32g/只。鱼虾混养总产量为3730kg/hm^2，比单养鱼或虾增产。     

克氏原螯虾池塘不同放养密度条件下养殖模式化试验

在江苏泰州市姜堰区沈高镇溱湖龙虾养殖专业合作社,进行克氏原螯虾池塘不同放养密度条件下模式化养殖试验。试验池4口,编号1#、2#、3#、4#,面积分别为11×667m2、14×667m2、10×667m2、15×667m2,克氏原螯虾苗种放养规格为380尾/kg,放养密度1#、2#为6000尾/667m2,3#、4#为12000尾/667m2,4口池每667m2搭配40尾规格约100g/尾的鲢。1#、2#池共收获克氏原螯虾76216尾、4740kg,667m2均产量189.6kg,平均规格62.2g/尾,回捕率50.8%,667m2利润4915.2元;3#、4#池共收获克氏原螯虾120790尾、4020kg,667m2均产量160.8kg,平均规格33.3g/尾,回捕率40.3%,667m2利润3164元。     

尼罗罗非鱼池塘精养高产试验

池塘规模化养殖罗非鱼效益显著,值得推广。本文报道了罗非鱼规模化养殖的技术和方法。从2004年5月19日放养8—9cm单性尼罗罗非鱼种27万尾,经过7个月养殖试验测定共存活24.84万尾,成活率92%,平均体重0.75kg/尾,最大体重0.81kg/尾。     

台湾泥鳅池塘高效养殖技术试验

利用200m~2的小试验池和0.267hm~2的池塘开展台湾泥鳅夏花培育及成鳅养殖试验。小试验池夏花泥鳅苗成活率约为35%;成鳅总产量1872.5kg,平均规格50.4g/尾,成活率70.1%。0.267hm~2的池塘成鳅总产量510.6kg,平均规格85g/尾,成活率约76.2%。     

墨瑞鳕大棚水泥池养殖技术试验

为调整上海郊区的水产养殖结构,开发水产新品种,提升养殖效益,2021年在上海市郊某合作社开展了墨瑞鳕(Maccullochella peelii)大棚水泥池养殖试验。试验采用2口大棚水泥池,投放经标粗培育的平均体质量为150 g/尾的墨瑞鳕大规格鱼种,放养密度为25尾/m²,全程投喂粗蛋白质质量分数43%的海水鱼膨化饲料。经过13个月养殖,共收获墨瑞鳕商品鱼9 576 kg(单位产量13.3 kg/m³,平均规格696.2 g/尾),饲料系数为1.58,单位产值为1 030元/m³。墨瑞鳕大棚水泥池养殖试验成功,对水产养殖结构调优具有一定的借鉴作用。     

Production of Florida red tilapia in seawater pools: Nursery rearing with chicken manure and growout with prepared feed

Florida red tilapia (Oreochromis sp.) were reared in 23 m³ seawater (37 ppt) pools. Monosex males (1.3 g mean weight) were stocked at a density of 25 fish/m³ and reared to fingerling size (>10 g) in pools receiving either chicken manure applied at a rate of 105 kg/ha day⁻¹ or pelletized feed (30% protein) administered ad libitum. Following the nursery period, fingerlings in fed pools were reared through adult, marketable sizes.

After 20 days of nursery rearing, mean fish weights (5.7–9.6 g) and survival (77.5–98.6%) in manured pools ranged from less than to greater than values in fed pools (7.9–9.4 g and 95.5–98.2%). By day 33, while mean weights (11.3±0.4 g) and survival (84.5±5.2%) in manured pools were significantly less than those in fed pools (18.0±0.6 g and 95.9±1.4%), fingerling-size fish were obtained from manured pools at an overall productivity of 55 kg/ha day⁻¹.

After 170 days in fed pools, mean fish weight was 467±9 g, survival was 89.7±0.9%, and food conversion was 1.6±0.2. Daily weight gain achieved a maximum of 4.4 g day before a rapid decline in water temperature from 28–29°C to 24–25°C caused a loss of fish appetite and evidence of disease.

The results suggest that while nursery rearing of Florida red tilapia in seawater pools fertilized with chicken manure is feasible, considerable variability in fish performance among pools can be expected, despite identical management methods. In pools receiving prepared feed, high growth rates and survival through adult, marketable sizes suggests a potential for commercial production of Florida red tilapia in seawater.     

Productivity and Economics of Nile Tilapia Oreochromis niloticus Cage Culture in South-East Brazil

ABSTRACT

Fish cage culture is an intensive, continuous-flow fish farming system, allowing intensive exploitation of water bodies with relatively low capital investment. This study aimed to determine the production function of Nile tilapia, Oreochromis niloticus, in cages; the profit-maximizing biomass at 300–400 and 500–600 fish per m³ for cages of different volumes; and the influence of water body conditions in fish performance. Feed intake, survival rate, and water temperature were monitored daily; dissolved oxygen, pH, and transparency of water were monitored each 15 days. Caged tilapia were fed daily on commercial, floating pellets (32% crude protein) at 0900, 1300, and 1700, and feeding rate was adjusted based on weight gain and survival rate. Data were analyzed statistically by ANOVA (P = 0.05) and regression analysis; the Mitscherlich function was chosen to represent the production function. Carrying capacity of both stocking densities reached 200 kg/m³ and no differences were found (P > 0.05) regarding accumulated biomass and individual average weight over time. The larger stocking density yielded larger accumulated biomass and had better feeding efficiency and no differences between individual average weights of fish at both densities were observed (P > 0.05). Profit-maximizing biomass at 500–600 fish/m³ was 145 kg/m³ and at 300–400 fish/m³ was 121 kg/m³. Cage farming of Nile tilapia at 500–600 fish/m³, individual average weight 283 g, presented many advantages: optimization of space and production time, better feed efficiency, higher fish production per unit volume of cages, and increased profitability.     

Effect of a Dietary Mixture of Beneficial Bacteria on Growth Performance,Health Condition,Chemical Composition,and Water Quality of Nile Tilapia,Oreochromis niloticus Fingerlings

ABSTRACT

Effects of dietary supplementation of Bifidobacterium longhum, Bifidobacterium thermophilum, Bacillus subtilis, and Lactobacillus acidophilus on growth performance, health condition, body chemical composition, and water quality of Nile tilapia (Oreochromis niloticus) fingerlings were evaluated. Five experimental treatments in triplicate were fed a diet containing 30% crude protein supplemented with variable inclusion of bacterial mixture: control, T1, T2, T3, and T4 containing 0, 1.0, 2.0, 3.0, and 4.0 g bacterial mixture/kg diet, respectively. Fish fed the T4 diet had the highest final body weight, weight gain, specific growth rate, thermal growth coefficient, feed intake, and the best feed conversion ratio. No significant differences in body chemical composition of fish were observed in terms of dry matter, crude protein, lipid, ash, and energy content among all treatments. Probiotic supplementation showed no noticeable differences on haematological and biochemical blood parameters, except for packed cell volume, albumin, albumin/globulin ratio, aspartate transaminase, glucose, uric acid, triglycerides, and cholesterol. Conclusively, Nile tilapia fingerlings diet supplemented with evaluated probiotic with an optimal dietary supplementation of 4 g/kg diet improved growth performance and fish health without a negative impact on water quality. This supplementation could therefore be used as a probiotic in Nile tilapia fingerlings diet.     

驯化主养鳙鱼种的试验

本文报导北方寒冷地区用微型颗粒饲料在5．6亩的池塘中主养鳙鱼种，经131d的饲养，共产鱼种2433kg，平均亩产434．5kg，其中鳙鱼亩产305kg，占总产量的70．2％,平均尾重76．25g，成活率80％。     

Total and available tryptophan requirement of Nile tilapia,Oreochromis niloticus,fingerlings

The dietary total and available requirement of tryptophan of Nile tilapia fingerlings was determined using linear regression analysis. Six hundred fish (3.4 ± 0.0 g) were fed diets containing 296.4 g/kg of crude protein and 14.1 MJ/kg of digestible energy. Five extruded diets containing 2.5, 3.0, 3.4, 3.8 and 4.2 g/kg of total tryptophan were evaluated. Fish were fed four times a day during 45 days. Final body weight, weight gain, feed intake, feed conversion ratio and net protein utilization of fish fed Trp 3.4 and Trp 3.8 diets were improved compared to fish fed Trp 2.5 and Trp 4.2 diets. No significant differences in survival rate, whole‐body moisture and ash were observed. Whole‐body amino acid profile of fish fed different diets did not differ statistically (p > .05). Fish fed Trp 3.0 and Trp 3.4 diets showed higher tryptophan retention compared to fish fed Trp 2.5 and Trp 4.2 diets. Excepting blood glucose, no effects of dietary tryptophan on haematological parameters were observed. The dietary total tryptophan requirement of Nile tilapia fingerlings based on weight gain was estimated to be 3.4 g/kg (11.0 g/kg of dietary crude protein) or 3.0 g/kg of available tryptophan (11.0 g/kg of dietary digestible protein).     

Growth and survival rate of three genetic groups fed 28% and 34% protein diets

The strain by nutrition interaction in body weight and survival rate was examined by testing three genetic groups (Selection and Control lines of the GIFT strain, and Red tilapia) at two levels of protein in the diet (28% and 34%). The GIFT strain of Nile tilapia (Oreochromis niloticus) has been selected for high‐breeding values for body weight, whereas the Control was contemporaneously maintained and selected for breeding values of body weight close to the population mean. The Red tilapia (Oreochromis spp) was unselected at the time of the experiment. There were a total of 6000 fish at stocking in the study (2000 fish per genetic group). During the grow‐out period of 147 days, within each genetic group, the fish were randomly assigned to either a 28% or a 34% protein diet. Survival rate during grow‐out averaged 72%. A total of 4335 fish were harvested, with individual body measurements and survival recorded. The effect of genetic group accounted for the largest proportion of variation in body weight and survival, followed by sex and protein level. Across the two dietary protein levels, the GIFT strain had the highest growth. The difference in body weight between the Control and Red tilapia was not statistically significant (P > 0.05). Responses in growth to dietary protein levels also differed between genetic groups. No differences (P > 0.05) in body weight were found in the GIFT selection and Control fish fed 28% or 34% protein diets. However, body weight of Red tilapia was greater in the high‐ than in the low‐protein diet. In contrast to body weight, survival rate from stocking to harvest was affected by protein level. The high‐protein diet significantly improved survival rate, averaging 24% across the three strains. The overall results indicate significant effects of genetic group and dietary protein level on both body weight and survival rate; however, the interaction between strain and dietary protein levels was small and possibly unimportant for these traits. It is concluded that the 28% protein diet used in the selection programme for the GIFT strain results in the selection of genotypes that can perform well under commercial feeds.     

Overwintering tilapia, Oreochromis spilurus (Günther), fingerlings using warm underground sea water

Abstract.
The study was conducted to develop guidelines for high-density overwintering of tilapia in tanks using warm underground sea water. Seawater-acclimated fish of 20 g were stocked in 36 tanks at 250, 500 and 750/m³. Water flow was regulated at 0.1 and 0.2 l/kg fish/min. Fish were fed at the rates of 0.75% and 1.0% of biomass per day.
After 135 culture days, the mean individual weight gain and specific growth rate decreased, whereas feed conversion increased significantly ( P <0.0001) with the increase in stocking density. The condition factor at 500 and 750 fish/m³ was significantly lower ( P <0.0005) than at 250 fish/m³. However, stocking density had no significant effect on the survival rate. Significantly better specific growth rate, condition factor and feed conversion were observed at a water flow rate of 0.2 l/kg fish/min than at 01 l/kg fish/min. Significantly higher mean individual weight gain, specific growth rate, and survival rate were observed at 1.0%/day than at the 0.75%/day feeding rate. The findings indicate that the optimum stocking density for overwintering tilapia in tanks using warm underground sea water is 750 fish/m³ with a water flow rate of 0.1 l/kg fish/min and a feeding rate of 0.75%/day.     

Culture of Nile tilapia, Oreochromis niloticus (L.), at three stocking densities in outdoor concrete tanks using drainage water

Abstract. Effects of stocking density on water quality and on the growth, survival and food conversion of Oreochromis niloticus (Linnaeus) were evaluated. Fingerlings of tilapia (average weight 40.25 ± 94 g) were stocked in six 3.75-m³ concrete tanks at 16, 32 and 42.6/m³ and reared for 164 days. A water flow rate of 1 l/min/kg fish biomass was maintained in all the tanks. The growth rate was inversely related to stocking density with mean weights of 337.25g, 327.0g and 323.5g at the low, medium and high densities respectively. At harvest, standing crop biomass averaged 5.36 kg, 10.44kg and 13.24kg for the three densities. The respective food conversion ratios (FCR) were 1.85, 1.88 and 1.95, while the survival rates were 99.2, 99.6 and 95.9%. However, the survival rate, growth rate and food conversion efficiencies were not significantly different at the three stocking densities. Water quality did not deteriorate in different tanks as the oxygen was continuously replenished and metabolites and waste products removed by the water flowing through the tanks. These data suggest that culture of tilapia at a density of 42.6/m³ and production of 13.24 kg/m³ in 164 days with a production of 18–20 kg/m³ in a growing season (April-October) of 210 days is possible using the drainage water in flow-through water systems.     

Effect of sublethal toxicity of some pesticides on growth parameters, haematological properties and total production of Nile tilapia (Oreochromis niloticus L.) and water quality of ponds

The effects of sublethal doses of dimethoate (20, 10 and 5 mg L^?1) and malathion (2.0, 1.0 and 0.5 mg L^?1) on growth parameters, haematological properties and total production of Nile tilapia (12.0 cm length and 40.0 g weight) and water quality were studied in fibreglass tanks (3 m²) for 24 weeks. Results showed that malathion compounds were more toxic than dimethoate. The sublethal toxicity of pesticides decreased plankton abundance and water quality in fish ponds. In comparison with controls, sublethal levels of these pesticides led to a significant decrease (P<0.05) in final body weight, specific growth rate and normalized biomass index of fish. The survival rate of Nile tilapia decreased with increasing concentrations of pesticides. Feed utilization (total food consumed, feed conversion ratio and protein efficiency ratio) varied with pesticide treatments. The erythrocyte count, haematocrit value and haemoglobin content of Nile tilapia were slightly decreased with increasing concentrations of pesticides. In addition, serum protein decreased, while serum glucose and lipid increased. Further, glycogen, protein and lipid in fish muscle gradually decreased with increased pesticide concentrations. Pesticide residues in the liver, gills and muscles of fish increased with increased pesticide concentrations in fish ponds. Their bioaccumulation in the liver was higher than in gill or muscle, which had the lowest residues for these pesticides. On the other hand, total production, net returns and profitability of reared fish decreased with increasing of concentrations of pesticides. Generally, sublethal concentrations of two pesticides in aquatic areas led to degradation of water quality and fish production in ponds.