Relationships between circulating androgens,aggressive behaviour and breeding tubercles in males of the common bream <Emphasis Type="Italic">Abramis brama</Emphasis> L. in an aquarium environment

In this study, relationships between circulating androgens, aggressive behaviour and breeding tubercles in males of common bream Abramis brama were examined in an aquarium environment. The breeding tubercles of fish were counted, the number of attacks was quantified by male status and circulating rates of testosterone and 11-ketotestosterone from blood plasma were analysed using radioimmunoassay procedures. The results revealed that no significant differences were found between circulating testosterone and 11-ketotestosterone in territorial and nonterritorial males. Furthermore, no significant correlations were found between circulating androgens, androgens and aggression, androgens and tubercles and breeding tubercles and aggression in common bream by male status. However, territorial fish displayed a significantly higher level of aggressive behaviour and breeding tubercles than nonterritorial fish. In natural environments, the occurrence of breeding tubercles during the spawning season could contribute to identifying the behavioural status of common bream males.     

Reduced total hardness of fresh water enhances the efficacy of bathing as a treatment for amoebic gill disease in Atlantic salmon, Salmo salar L

The current treatment for amoebic gill disease (AGD)-affected Atlantic salmon involves bathing sea-caged fish in fresh water, often sourced from local dams, for 3-4 h. In both a small-scale laboratory and an on-farm field experiment, the effects of water hardness on the efficacy of freshwater bathing were assessed. Results showed that soft fresh water (19.3-37.4 mg L(-1) CaCO3), whether it be naturally soft city mains water or artificially softened dam water, was more efficacious at alleviating AGD in affected fish than hard fresh water (173-236.3 mg L(-1) CaCO3). Soft freshwater bathing significantly reduced viable gill amoebae numbers (from 73.9 to 40.9% of total count) and significantly alleviated gill pathology, both gross and histological. Following bathing, gross gill pathological scores of soft freshwater bathed fish lagged 2 weeks behind hard freshwater bathed fish. Significant gill lesion fragmentation, and shedding of lesion-associated hyperplastic tissue, was accompanied by a significant reduction in AGD-affected gill filaments in soft freshwater bathed fish. Furthermore, soft freshwater bathing alleviated the blood plasma electrolyte imbalance seen in control (sea water) and hard freshwater bathed fish. This study showed that the use of soft fresh water for bathing AGD-affected Atlantic salmon could be an improvement to the current method of treatment. Not only does it reduce gill amoeba numbers, but also, it is of a therapeutic advantage with the potential to reduce bathing frequency.     

Kidney tumour virus—tumour or mycobacterial tubercle?

Abstract. Bacteriologically sterile filtrates of 'tumorous' fish elicited formation of 'tumours' in vivo which were morphologically indistinguishable from those described by Wessing & Bargen (1959). Attempts to isolate the putative aetiologic 'Virus' in primary and established cell cultures failed. When the lesions were examined for other compatible aetiologies, acid-fast stains revealed acid-fast bacilli and cultures grew Mycobacterium fortuitum . It is suggested that the 'kidney tumour virus' is actually soluble mycobacterial cell-fractions capable of eliciting tubercle formation in vivo .     

Effect of potential probiotic bacteria on growth and survival of tilapia Oreochromis niloticus L., cultured in the laboratory under high density and suboptimum temperature

This study examined the effect of potential probiotic bacteria on growth and survival of the tilapia Oreochromis niloticus , under high density and suboptimum temperature. Presumptive Bacillus and lactic acid bacteria (LAB) were isolated from tilapia and from their culture system and were characterized for haemolytic and enzymatic activity, and antagonism against Vibrio . Selected strains were included in the diet of juvenile tilapia and evaluated during a 134-day assay. The experiment was conducted with four treatments: (1) fish fed with commercial feed plus Dry Oil^®; (2) fish fed with commercial feed plus LAB; (3) fish with bacilli in water; (4) fish with a mixture of treatments 2 and 3. Tilapias in all treatments, including bacteria, grew significantly better than fish fed with commercial feed plus Dry Oil^® (control group). Survival was similar in all treatments. The physicochemical parameters of the culture system were maintained within the optimal ranges for the species, with the exception of temperature (19.9–24.82 °C). Animals fed diet supplemented with bacilli and LAB had good survival and the best growth performance, suggesting that bacteria are appropriate growth-stimulating additives in tilapia cultivation.     

饲料种类对中华鳖营养成分的影响

以每立方米 0 .5只的密度放养体重为 2 5 0g左右的鳖种 ,分别投喂冰鲜鱼、30 %冰鲜鱼 +70 %配合饲料的混合饲料和配合饲料。养殖期 5个月 ,各取 6尾 6 0 0g左右的雄性商品鳖进行营养成分测定和比较。结果表明 :3种鳖的脂肪率、粗蛋白含量和脂肪酸组成差异不显著 (P >0 .0 5 )。但肌肉中的粗脂肪、氨基酸总量和鲜味氨基酸含量均极显著地以冰鲜鱼饲料饲喂的鳖为高 (P <0 .0 1)。肌肉与裙边组织中的氨基酸总量、必需氨基酸和鲜味氨基酸的积累与饲料中相应的氨基酸含量呈显著的相关关系 (r1=0 .784 3,r2 =0 .90 6 2 ,P <0 .0 1) ,其积累量随饲料中含量变化而变化。饲料对商品鳖的风味和营养价值有一定的影响。     

大弹涂鱼土池产卵技术探讨

选择投放产卵器和自然人工生态育苗两种方式进行大弹涂鱼（Boleophthalmus pectinirostris）人工育苗试验,通过清除敌害、调控水位、分批出苗的方法人工培育大弹涂鱼。结果显示,底质较硬的养殖池,投放产卵器可以获得受精卵,而长期用于大弹涂鱼养殖的土质较软的泥滩地,亲鱼则更倾向于直接钻洞产卵孵化;证明大弹涂鱼在池塘养殖条件下能够自然繁殖。     

鱼肉汉堡包软罐头制作工艺研究

为利用资源丰富的大宗鱼类开发水产软罐头食品,进行了鱼肉汉堡包软罐头制作工艺技术的研究,对配料和加热灭菌条件作了调试,以期得到能在常温下流通的方便即食食品     

Fish mycobacteriosis: morphopathological and immunocytochemical aspects

Abstract. A morphopathological study of fish tuberculosis was carried out using histological and immunocytochemical techniques. The clinical signs observed were emaciation, lack of movement coordination and body deformation. Macroscopically, small, light-coloured, visceral nodules were detected. Immunocytochemical techniques were found to be effective in detecting infections where conventional staining methods failed to reveal, or detected only small numbers of bacilli.     

科技进步对我国农户精养淡水鱼生产贡献率实证分析

淡水鱼是我国水产品之一，定量分析科技进步对我国淡水鱼产量贡献具有积极的现实意义。本文在综述科技进步定义和测定方法的基础上，选择基于前沿生产函数和技术效率分析原理的科技进步测定方法，并以2002年和2003年我国主要省市农户精养淡水鱼成本收益资料为样本，应用SPSS统计分析软件测定了我国主要省市在2002—2003年的硬技术进步贡献率、软技术进步贡献率及要素投入贡献率，结论为就全国平均水平而言，软技术进步对我国农户精养淡水鱼产量有负效应影响：我国农户精养淡水鱼生产存在着明显的差异性和不均衡性；我国存在五种类型的农户精养淡水鱼生产区域。．     

Polychaetes as indicators of marine fish farm organic enrichment

Marine fish farms cause environmental disturbance of sediment due to uneaten food and fish faeces that accumulate on the sea bottom. These products give rise to organic enrichment followed by degradation processes; reduction of level of dissolved oxygen in the bottom water; generation of high levels of sulfides; changes of benthic assemblages and even azoic conditions. The soft bottom benthic communities and, above all, the polychaetes are considered good indicators of environmental perturbations considering their relatively fast changes in diversity and abundance and because their trophic flexibility and life-history traits are considered a pre-adaptation to the condition of disturbed habitats. The aim of the present study is to evaluate the polychaete population changes as a result of organic enrichment produced by a marine fish farm. The study was carried out on a fish farm located in the coastal water of Porto Ercole (Tyrrhenian Sea) with two submersible sea cages and a year production of 180 tonnes. The macrobenthos samples were collected during four campaigns (July and December 2001, May and October 2002). The results showed: 1) a rapid change of the assemblage located beneath the cages related to the fish biomass reared and a high dominance of the opportunistic Capitella spp.; 2) limited sediment disturbance close to cages (20–50 m); 3) no effect in the area 50 m beyond the cages. Two months after the fish harvest and thus reduction of organic enrichment, perturbated assemblages showed signals of recovery like species richness increase and reduction of opportunistic species.     

巨魾的生物学特性初步研究

对巨魾（Bagarius yarrelli Sykes）栖息江河进行实地调查了解,并解剖61尾体长20．4-43．5cm、体重124—1200g的野生巨魾研究其内脏器官特点,还对野生活体巨魾进行人工驯养研究。研究了解了巨魾外部形态结构特征和消化系统的组成;计算肠长与体长比值为1．19;确定巨魾食性为底栖肉食性鱼类。     

鲤鱼棘头虫病的病理及预防

本文报导了病鱼的组织(肠、肝、胰、肾)病理变化,及血液(血清的钠、钾、氯化物、肌酐、尿素氮、谷草转氨酶总活力及谷草转氨酶同工酶。白细胞血式)病理变化,从而阐明了引起病鱼慢性死亡,而累计死亡率又高达60％的机理。查明了病原(崇明长棘吻虫)的中间寄主是模糊裸腹溞,找到了用生石灰或漂白粉清塘、在发病地区用鱼种池培育的鲤鱼鱼种的有效预防方法。     

Creating wetland islands to enhance shoreline habitat for fish recruitment in a modified shallow lake

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软质饲料与鲜杂鱼饵料饲养大黄鱼对比试验

为比较研究网箱养殖大黄鱼过程中分别投喂软质饲料与鲜杂鱼饵料的养殖效果,2011年5月于福建省马鼻玉井网箱养殖海区,选取平均规格为152 g/尾的大黄鱼,经过60 d的饲养,试验组全投软质饲料,对照组全投鲜杂鱼。结果显示：试验组与对照组每尾平均体重分别为256.9 g、231.3 g,饲料系数分别为2.505、7.306,大黄鱼每增重1 kg所需的饲料成本分别为15元、19.7元,投喂软质饲料进行饲养可节省成本4.7元。结果表明：投喂软质饲料的养殖效果优于鲜杂鱼,存活率更高,更具环保等综合效益。     

Automated measurement of species and length of fish by computer vision

Trials of a computer vision machine (The CatchMeter) for identifying and measuring different species of fish are described. The fish are transported along a conveyor underneath a digital camera. Image processing algorithms: determine the orientation of the fish utilising a moment-invariant method, identify whether the fish is a flatfish or roundfish with 100% accuracy, measure the length with a standard deviation of 1.2 mm and species with up to 99.8% sorting reliability for seven species of fish. The potential application of the system onboard both research and commercial ships is described. The machine can theoretically process up to 30,000 fish/h using a single conveyor based system.     

大银鱼混合营养期的人工投饵实验

报道了大银鱼混合营养期投喂小球藻,金藻,裸藻以及微粒仿生饲料的实验结果,其效果依次为金藻〉微粒仿生饲料〉小球藻〉裸藻。并观察了混合营养期仔鱼的形态变化,为大水面移植和小水体养殖大银鱼提供了理论依据。     

基于鱼类食性的白洋淀食物网研究

2009年6月至2010年5月,对白洋淀8个典型采样点进行了调查,分析了白洋淀鱼类的食性、营养级和食物网特征,绘制了鱼类食物网及能量流动途径。结果显示,白洋淀现有鱼类25种,其食性类型分为草食性、浮游生物食性、底栖生物食性、游泳动物食性、浮游生物+底栖生物、底栖生物和游泳动物食性共6种;白洋淀的鱼类营养级可分为草食性、杂食性、低级肉食性、中级肉食性和高级肉食性共5种。与历史资料相比,白洋淀鱼类食物网趋于简单,中级肉食性鱼类匮乏,能量流动出现越级现象,食物网结构不完整,说明其渔业资源遭受严重破坏。     

'No-mucus skin disease' of rainbow trout, Oncorhynchus mykiss (Walbaum): a case report

Abstract A skin disease of intensively reared salmonids in Ontario hatcheries, known to the farmers as'no-mucus skin disease', is reported for the first time. It was characterized by erosive and ulcerative lesions found mainly on the flanks of fingerlings, which resulted in exposure of the tips of the scales. Associated with these lesions were colonies of bacteria seen in the SEM to be clustered round the mucous cell pores and under-running the margins of epithelial cells. The cause of this condition is unknown, although the response of fish to formalin treatment, and the presence of bacilli seen in skin scrapings and in the SEM, suggest that bacteria are responsible.     

Vitamin A functions and requirements in fish

Vitamin A (VA) is an essential dietary nutrient for fish and plays an important role in a range of physiological processes including vision, reproduction, embryogenesis, growth and differentiation and maintenance of epithelial cells. Knowledge of effects of VA on aquatic organisms is limited, but new information continues to be published. The aim of the present review is to present an overview of the dietary requirements and functions of VA in fish of commercial importance in aquaculture production. The effects of VA on reproduction and early embryonic development are described, and the estimated dietary requirements for VA of several species of fish are discussed. New research findings on how VA requirements vary with the life stages of fish are explored that will expand understanding of the complex role of VA. Sources of VA in feeds are described, and the potential need to consider how changes in fish feed formulations towards higher use levels of sustainable ingredients may affect dietary VA supplementation recommendations is discussed.