积温和放养规格对网箱养殖罗非鱼的影响

利用大秋房水库网箱养罗罗非鱼的６年生产记录，以放养规格以及每天大于１５℃、大于２０℃的积温和天数作为自变量、以个体增肉倍数、饵料系数作为变量，进行一元和二无回归分析。结果发现：每天大于１５℃的积温和天数与增肉倍数相关最显著；第天大于１５℃的天数和放养规格与饵料系数相关也较显著。     

网箱养殖模式下投喂率对吉富罗非鱼生长性能的影响

为了解吉富罗非鱼养成中期和后期最适投喂率,于吉富罗非鱼养成中期设置6个试验组(1.50%,2.00%,2.50%,3.00%,3.50%和4.00%),于养成后期设置4个试验组(1.50%,2.00%,2.50%和3.00%)开展养殖试验。周期分别为60和72 d。结果显示,养成中期,吉富罗非鱼的体质量增加率随投喂率的增加而增大;饲料系数随投喂率的增加则呈现先降低后升高的趋势,投喂率为2.00%组最低;投喂率对罗非鱼的肥满度、肝体比和脂体比有显著影响(P<0.05)。养成后期,吉富罗非鱼的体质量增加率随投喂率的增加呈先升高后降低的趋势;饲料系数随着投喂率的增加而增大,投喂率为1.5%时最低,投喂率为3.0%时最高。指出,在网箱养殖模式下,分别以获得最大体质量增加率和最低的饲料系数为评价指标,养成中期吉富罗非鱼适宜投喂率分别为4.02%和1.96%,养成后期分别2.56%和1.50%。     

池塘网箱养殖鲤鱼与罗非鱼试验

随着社会发展及城市化进程的加快,人口数量急剧增加,土地资源和水资源量的锐减,人类对水产品的需求增大与水产生产资源锐减的矛盾日益突出,成为制约水产养殖发展的瓶颈问题,传统的养殖模式受到了挑战。发展高效、环境友好型渔业成为水产养殖持续发展的首选。由天津     

网箱的水深对莫桑比克罗非鱼生长及体形的影响

有关养鱼池构造的报告．多数从水的畅通、水循环等方面和渔获作业有利与否来研讨。而利用鱼的习性建造鱼池的问题却不怎样研究。水深是影响鱼类生长的重要因素之一．决定养鱼池中各种鱼的合适水深．以前的资料是很不充分的。作者等为了获得按照鱼的习性建造养廸设施的基本资料．着手进行水深问题的试验。     

不同盐、碱度下3品系尼罗罗非鱼幼鱼网箱养殖的生长比较

以慢性驯化后的上海、山东、河北品系尼岁岁非鱼（Oreochromis niloticus）幼鱼为试验材料,比较它们在盐度组（0、15和20）、碳酸氢钠（NaHCO3）碱度组（1 g·L^-1、2 g·L^-1和3 g·L^-1）以及盐碱混合组（15,1 g·L^-1;15,2 g·L^-1;15,3 g·L^-1;20,1 g·L^-1;20,2 g·L^-1和20,3 g·L^-1）条件下网箱养殖成活率和日均增重率差异.62d试验结果表明,上海、山东、河北品系尼罗罗非鱼幼鱼在不同盐度、碱度、盐碱混合处理组中的成活率差异不显著（P＞0.05）,而日均增重率的差异显著（P＜0.05）.随着盐度、碱度增加,尼罗罗非鱼生长速度大体呈下降趋势;盐碱混合组生长速度较单盐、单碱组减慢.还发现不同品系尼罗罗非鱼在不同盐碱梯度下表现出不同的相对生长优势.研究结果为尼罗罗非鱼适宜养殖的盐碱范围确定、品系筛选提供了重要的基础资料.     

深水网箱和池塘养殖凡纳滨对虾肌肉营养成分的比较分析

对深水网箱和池塘养殖凡纳滨对虾(Litopenaeus vannamei)肌肉常规营养成分、氨基酸和脂肪酸质量分数进行了比较分析。结果显示:1)网箱养殖对虾肌肉粗蛋白质量分数显著高于池塘养殖(P0.05),而水分、粗脂肪和粗灰分质量分数无显著差异(P0.05);2)肌肉中检测到18种常见氨基酸,网箱养殖对虾肌肉氨基酸总量(TAA)、天门冬氨酸(Asp)、异亮氨酸(Ile)、精氨酸(Arg)和脯氨酸(Pro)质量分数显著高于池塘养殖(P0.05),而必需氨基酸(EAA)、半必需氨基酸(HEAA)、鲜味氨基酸(DAA)和虾味氨基酸(PFAA)两者无显著差异(P0.05);3)肌肉中检测到30种常见脂肪酸,两者的饱和脂肪酸(SFA)、单不饱和脂肪酸(MUFA)、多不饱和脂肪酸(PUFA)、n-3多不饱和脂肪酸(EPA和DHA)质量分数差异显著(P0.05),以网箱养殖对虾较高;两者的棕榈酸(C16∶0)质量分数最高,且网箱养殖对虾EPA+DHA质量分数是池塘养殖的1.90倍。结果表明,网箱养殖对虾营养成分要优于池塘养殖,具有较高的营养价值。     

木薯粉对罗非鱼生长、饲料利用和鱼体营养成分的影响

选择健康的吉富罗非鱼(体重1.29±0.25 g)为实验鱼,配制五种木薯粉含量分别为0%、10%、20%、30%和40%的等氮(粗蛋白为32%)、等能(总能为16 kJ·g-1)实验饲料,饲喂罗非鱼56 d,每饲料组设三个重复,研究不同含量木薯粉对吉富罗非鱼生长、饲料利用及全鱼营养成分的影响.结果表明:(1)木薯粉能提高罗非鱼的增重和蛋白质效率,其中以40%木薯粉组的效果最佳,其增重率、蛋白质效率和饲料系数分别为1470.99%(P＜0.05)、2.36(P＜0.05)和1.27(P＜0.05).(2)40%木薯粉组的干物质和蛋白质的表观消化率分别较对照组提高13.87%(P＜0.05)和7.93%(P＜0.05).(3)40%木薯粉组的全鱼粗蛋白、粗灰分分别较对照组显著提高7.07%(P＜0.05)和8.78%(P＜0.05),粗脂肪降低了13.00%(P＜0.05).     

池塘循环水槽养殖模式下吉富罗非鱼的生长及生理响应变化

为探讨在池塘循环水槽养殖模式下吉富罗非鱼不同养殖密度的生长特性和生理指标变化,评估吉富罗非鱼在池塘循环水槽养殖模式下的适宜养殖密度,以吉富罗非鱼为实验对象,设计传统池塘养殖模式放养密度5尾/m² (SD1组),池塘循环水槽养殖模式放养密度180尾/m² (SD2组)和270尾/m² (SD3组),比较各组吉富罗非鱼的生长性能,分析血液生化指标和肝脏HSP70 mRNA表达量的变化规律。结果显示,经过120 d的养殖,SD2组吉富罗非鱼终末体质量、特定生长率和绝对生长率显著高于SD1和SD3组。SD2和SD3组存活率、体质量差异系数和饵料系数低于SD1组。SD2组血清皮质醇、血清谷丙转氨酶、谷草转氨酶、溶菌酶水平和肝脏HSP70 mRNA的相对表达量在30 d时显著高于SD1组。SD3组血清皮质醇和葡萄糖水平在60 d后持续上升,120 d时显著高于SD1组,谷丙转氨酶、谷草转氨酶、溶菌酶水平和肝脏HSP70 mRNA的相对表达量在60、90 d时显著高于SD1组,甘油三酯在整个实验期显著低于SD1组。SD2组吉富罗非鱼在...     

不同盐度对尼罗罗非鱼存活和生长性能的影响

为评估选育耐盐尼罗罗非鱼(Oreochromis niloticus)在高盐度水体中的生长性能,在塑料盒(80cm×60cm×60cm)中设置盐度21‰、24‰、27‰和29‰共四个盐度梯度处理进行耐盐鱼苗的生长性能比较研究。养殖40d的生长结果表明,随着盐度的逐步增加,选育尼罗罗非鱼苗存活率呈明显下降的趋势,且日增重、增重率以及特定生长率等指标也均呈下降趋势。耐盐选育尼罗罗非鱼可以在29‰的盐度下正常生长,且存活率可达80%以上,本试验为尼罗罗非鱼在半咸水地区养殖提供基础数据。     

土池网箱育苗中放养密度对刺参生长及成活的影响

2009年5-10月,在长40 m、宽20 m、水深1.6～2.0 m,池底以内缝遮阳网的旧养貂笼为支架的土池内,放置长3.0m、宽2.0m、高2.0m的网箱,上覆遮阳网,内放30～35串1.2m长的筛网(8～12层).每个网箱分别放入体质量为0.003～0.0169 g的刺参苗500 g(A组为小规格、B组为大规格)...     

Phenotypic and genotypic characterization of Streptococcus spp. isolated from tilapia (Oreochromis spp.) cultured in river-based cage and earthen ponds in Northern Thailand

Streptococcus spp. are major pathogenic bacteria associated with massive mortality in tilapia. This study investigated the phenotypic and genotypic characterization of Streptococcus agalactiae (GBS) and Streptococcus iniae (S. iniae) isolated from tilapia in river-based floating cage and earthen pond farms in northern Thailand. Isolates were identified by biochemical and molecular analyses. Capsular typing, enterobacterial repetitive intergenic consensus polymerase chain reaction and multilocus sequence typing were performed to investigate the genetic relatedness. Six and one isolates were confirmed as GBS and S. iniae, respectively. All Streptococcus spp. isolates were obtained from 4 river-based cage farms (4/33), while samples collected from earthen pond farms (N = 28) were negative for streptococcosis. All GBS with serotype Ⅲ and sequence type (ST) 283 was observed. The β-haemolytic GBS isolates were resistant to five antimicrobials, while the S. iniae was susceptible to all antimicrobials. This study indicates both GBS and S. iniae are the major bacterial pathogens responsible for streptococcosis infection in farmed tilapia of northern Thailand with GBS as dominant species. This survey highlights that the river-based cage farms seriously impact on the healthy development of the tilapia industry.     

Effect of organic nitrogen and carbon mineralization on sediment organic matter accumulation in fish ponds

In aquaculture, ponds with high loads of organic inputs, organic matter accumulates at the bottom over time. Uneaten feed, senescent phytoplankton and faeces are the principal sources of accumulated material, but quantifications are scarce. The sedimented organic matter develops into a flocculent layer in which different processes transform the material into inorganic forms. A better understanding of factors influencing organic matter accumulation/decomposition in the sediment is needed to better understand and manage the dynamics of nitrogen in fish ponds. In this study, the rate of mineralization of organic nitrogen and the nitrogen flux between the sediment and the water column were measured. Organic matter accumulation in fish ponds was quantified, and the data were used to construct, calibrate and validate a dynamic simulation model of organic matter deposition/decomposition in fish ponds. The accumulating material consisted of dead phytoplankton, fish faeces and uneaten feed. Through model calibration, the proportion of these materials in the total accumulated organic matter was determined. In the model, gross photosynthetic rate was estimated from an empirical relationship with feed input. After calibration, the model was validated using independent data. The model simulated well the concentrations of organic carbon and nitrogen in the sediments but it may be developed further, especially by considering the effects of resuspension.     

Response of Nile tilapia (Oreochromis niloticus) to diet acidification: Effect on growth performance and feed utilization

A 12-week feeding trial was undertaken to assess growth, nutrient utilization, some hematological parameters, and proximate composition of Nile tilapia (Oreochromis niloticus) fed diets supplemented with graded levels (0.5%, 1.0%, and 1.5%) of two blends of organic acids or organic salts. Seven isonitrogenous (300 g CP kg^?1) and isocaloric (19.0 MJ gross energy kg^?1) diets were formulated. The control diet (D1) contained neither added blend of organic acids nor organic salts. Three diets (D2, D3, and D4) were supplemented with 0.5%, 1.0%, and 1.5% of malic acid + oxalic acid blend (OAB), respectively. The other three diets (D5, D6, and D7) were supplemented with 0.5%, 1.5%, and 1.5% of calcium lactate + sodium acetate blend (OSB), respectively. Fingerlings (7.05 ± 0.02 g) were randomly distributed into 21 glass aquaria (160 liter), with each aquarium holding 15 fish. At the end of the feeding trial, O. niloticus offered the control diet showed lower growth and feed utilization than all those fed the organic acids or organic salts blends supplemented diets. Fish fed the diet D3 showed the highest body weight (BW), body length (BL), weight gain (WG), specific growth rate (SGR), feed intake (FI), and the best feed conversion ratio (FCR) and protein efficiency ratio (PER). Fish fed diet supplemented by 1.5% OAB (D4) showed the highest serum protein content, while control group (D1) showed the lower level of total lipids compared with the other treatments. Fish group fed the diet supplemented with 0.5% of OSB (D5) showed the highest protein and ash contents and the lowest lipid content of the whole fish body, while the control group showed the lowest protein and the highest fat content. The present observations suggest that the growth, feed utilization, and health status of juvenile O. niloticus can be enhanced with a supplementation of 1% of OAB or OSB in the diet.     

Quantitative and qualitative studies on bacterial flora of hybrid tilapia (Oreochromis niloticus × O. aureus) cultured in earthen ponds in Saudi Arabia

The bacterial flora of the rearing pond water and sediment as well as the gills and intestine of healthy hybrid tilapia cultured in Saudi Arabia was estimated quantitatively and qualitatively, the isolates being identified at genus or species level. Total viable counts of bacteria (measured as colony‐forming units, cfu) were in the range 5.6 ± 0.8 × 10³ to 2.4 ± 1.2 × 10⁴ cfu mL^?1 in pond water; 9.3 ± 1.1 × 10⁶ to 1.9 ± 1.5 × 10⁸ cfu g^?1 in sediment; 7.1 ± 0.7 × 10⁵ to 8.7 ± 1.1 × 10⁶ cfu g^?1 in the gills of tilapia; and 3.4 ± 1.8 × 10⁶ to 5.8 ± 0.4 × 10⁷ cfu g^?1 in the intestine of tilapia. In total, 15 bacterial genera and 18 species were identified. Pond water and sediment bacteria reflected the bacterial composition in the gills and intestine of tilapia. In contrast to gill bacteria, more diversification was observed in intestinal bacteria. Corynebacterium urealyticum, Shewanella putrefaciens and Aeromonas hydrophila predominated in all samples. In pond water, C. urealyticurn, S. putrefaciens, A. hydrophila, Flavobacterium sp. and Pseudomonas sp. were the most predominant bacterial species (prevalence > 10%), whereas A. hydrophila, C. urealyticum, S. putrefaciens and Escherichia coli were predominant in pond sediment, and C. urealyticum, S. putrefaciens and A. hydrophila were predominant in both the gills and intestine of tilapia.     

三沙湾大黄鱼网箱养殖衍生有机物的沉降特征

为了解三沙湾大黄鱼（）网箱养殖衍生有机物（AOM）的沉降特征,采用原位实验方法,收集区域内使用颗粒饲料和冰鲜饵料两种典型饲喂方式下距离网箱200 m范围内AOM样品,分析其沉降量、营养物质[颗粒有机物（POM）、颗粒有机碳（POC）、颗粒态氮（PN）、总磷（TP）]沉降通量和扩散特点。研究结果表明,饲喂颗粒饲料状态下AOM沉降量显著高于投喂冰鲜饵料,两者均值分别为（563.66±119.18）g/（m²·d）和（266.07±139.15）g/（m²·d）。POM、POC、PN和TP沉降通量在两种饲喂方式下的差异与之相似,饲喂颗粒饲料时各参数均值分别为（27.25±2.43）g/（m²·d）、（6.03±0.58）g/（m²·d）、（0.66±0.06）g/（m²·d）和（0.39±0.04）g/（m²·d）;饲喂冰鲜饵料时各参数均值分别为（13.04±1.62）g/（m²·d）,（3.57±0.45）g/（m²·d）、（0.51±0.06）g/（m²·d）和（0.22±0.04）g/（m²·d）。沿近底层海流主导流向距离养殖网箱100 m的空间范围内,AOM沉降量和营养物质沉降通量均呈现自网箱处递减的变化特征,下降程度在饲喂冰鲜饵料时尤为显著。AOM中POC、PN和TP含量在饲喂冰鲜饵料时较高,在距离养殖网箱50 m范围内呈现递减趋势。综上,在三沙湾大黄鱼网箱养殖过程中,投喂颗粒饲料引发的环境污染程度高于冰鲜饵料,两种情形下的AOM沉降影响主要限于距离养殖网箱50~100 m的空间范围。三沙湾内饲喂颗粒饲料引发较高营养物质沉降通量源于较大的AOM沉降量,此现象说明养殖过程中可能存在颗粒饲料过度投喂、饵料利用效率较低等问题,围绕此类问题的针对性研究对于减缓区域内养殖活动的环境影响具有重要意义。     

Effects of tilapia (Oreochromis niloticus L.) stocking and artificial feeding on water quality and production in rohu–common carp bi‐culture ponds

Previous research showed that stocking 1.5 rohu (Labeo rohita) and 0.5 common carp (Cyprinus carpio) m⁻² yields the highest production in small holder ponds in Bangladesh. The present study looked into the effects of additional stocking of Nile tilapia (Oreochromis nilotica) in fed or non‐fed ponds on water quality and fish production. A low, additional stocking density of 0.2 Nile tilapia m⁻² was tested. All treatments were executed in triplicate in 100 m² ponds and the duration of the experiment was 4.5 months. The results showed that tilapia addition increased nutrient concentrations and reduced total suspended solid concentration and phytoplankton biomass (P<0.05). Tilapia stocking resulted in additional production without affecting the growth and production of rohu and common carp. Supplemental feeding increased the nitrogen and phosphorus concentrations, phytoplankton availability and the growth and production of rohu and common carp (P<0.01). The combination of supplemental feeding and tilapia stocking resulted in a higher net yield than the other treatments (P<0.05). Stocking 1.5 rohu, 0.5 common carp and 0.2 tilapia m⁻² in fed‐ponds is a good culture combination for polyculture farmers in South Asia.     

Culture of organic tilapia to market size in periphyton‐based ponds with reduced feed inputs

In fish production under organic standards, only organic feeds and manures can be supplied. The cost of organic pelleted feeds is twice that of regular feeds. To support the organic production of hybrid tilapia [Oreochromis niloticus (L.) ×Oreochromis aureus (Steindachner)], a series of experiments in earthen ponds, to improve natural food production for this fish while reducing costs of added feed, are in progress. To improve natural food production for tilapia, plastic substrates equivalent to 50% of the pond surface were introduced into the water column to induce periphyton growth on them. To reduce costs, the feeding rate on pelleted feed was reduced to 60%. Tilapia growth in these periphyton ponds was then compared with ponds without underwater substrates that received the full feed rate. The polyculture consisted of 90% large (320 g stocking weight) hybrid tilapia and small amounts of other fish, at a total stocking density of 13 800 fish ha^?1, during 87 summer days. The results showed improved nitrification and the development of a large autotrophic periphyton biomass that competed with the phytoplankton in the periphyton ponds, and only a 10% and 15% reduction, respectively, in the tilapia daily and specific growth rates, with 40% feed saving. These results point towards periphyton‐based aquaculture as an appropriate technology for the reduction in production costs, allowing economically viable organic tilapia production.     

Heritability estimates and response to selection for growth of Nile tilapia (Oreochromis niloticus) in low-input earthen ponds

This study presents results of two generations of selection (G₁ and G₂) for growth of Nile tilapia. The selection environment consisted of earthen ponds which were fertilized daily with 50 kg dry matter (dm)/ha chicken manure. No supplementary feeds were provided. In total, 6429 fully pedigreed experimental fish were included in the analysis. Survival till harvest was highly variable ranging from 35% to 77% and was affected by initial weight, pond, and age effects. Body weight at harvest (BW) increased from a mean of 67.4 g in the grandparental (unselected) population (G₀) to 129.5 g in G₂ was affected by initial weight, pond, sex and age effects. Generations were discrete and therefore genetic parameters were estimated separately for each year. Heritability estimates for BW ranged from 0.38 to 0.60, and the heritability for survival ranged from 0.03 to 0.14. The estimated selection response was 23.4 g (34.7%) between G₀ and G₁ and 13.0 g (14.9%) between G₁ and G₂. These results demonstrate the feasibility of selection for growth of Nile tilapia in low-input environments.     

Effects of dietary L‐lysine supplementation on growth,body composition and muscle‐growth‐related gene expression with an estimation of lysine requirement of GIFT tilapia

An 8‐week feeding trial was conducted with extruded practical diets containing 320 g/kg of crude protein from plant‐based sources to determine the effects of L‐lysine on growth performances, muscle‐growth‐related gene (myoD, myogenine and myostatin) expression and haemato‐biochemical responses in juvenile genetically improved farmed tilapia (GIFT). Five isonitrogenous and isoenergetic diets were formulated to contain graded levels of lysine (14.3, 16, 17.5, 19 and 20.5 g/kg of diet). Each diet was randomly assigned to triplicate groups of 30 juvenile fish (5.2 ± 0.1 g), which were fed thrice a day (9:00, 13:00 and 17:00 hr). Maximum growth performances were observed in fish fed with lysine at 19 g/kg of diet. There was no significant (p > .05) effect on whole‐body composition and amino acids profile by dietary lysine supplementation. Significant (p < .05) changes were observed in relative expression of muscle‐growth‐related genes namely myoD and myogenine and in plasma metabolites by dietary lysine supplementation. In contrast, the relative expression of myostatin was not affected by dietary lysine supplementation. Broken‐line regression analysis and second‐order polynomial regression analysis of weight gain and N gain against dietary lysine levels showed that the dietary lysine requirement for juvenile GIFT tilapia was 18–18.3 g/kg of diet and 19.3–19.5 g/kg of diet, respectively.     

Cage‐pond integration of African catfish (Clarias gariepinus) and Nile tilapia (Oreochromis niloticus) with carps

Cage‐pond integration system is a new model for enhancing productivity of pond aquaculture system. A field trial was conducted using African catfish (Clarias gariepinus) and Nile tilapia (Oreochromis niloticus) in cages and carps in earthen ponds. There were four treatments replicated five times: (1) carps in ponds without cage, (2) tilapia at 30 fish m^?3 in cage and carps in open pond, (3) catfish at 100 fish m^?3 in cage and carps in open pond, (4) tilapia and catfish at 30 and 100 fish m^?3, respectively, in separate cages and carps in open pond. The carps were stocked at 1 fish m^?2. The cage occupied about 3% of the pond area. The caged tilapia and catfish were fed and the control ponds were fertilized. Results showed that the combined extrapolated net yield was significantly higher (P < 0.05) in the catfish, tilapia and carps integration system (9.4 ± 1.6 t ha^?1 year^?1) than in the carp polyculture (3.3 ± 0.7 t ha^?1 year^?1). The net return from the tilapia and carps (6860 US$ ha^?1 year^?1) and catfish, tilapia and carps integration systems (6668 US$ ha^?1 year^?1) was significantly higher than in the carp polyculture (1709 US$ ha^?1 year^?1) (P < 0.05). This experiment demonstrated that the cage‐pond integration of African catfish and Nile tilapia with carps is the best technology to increase production; whereas integration of tilapia and carp for profitability.