黑鲷鱼种低盐度培育试验

海盐县地处杭州湾北岸,常年海水盐度4～10。2003年至今我们在海盐县秦山镇杨柳山村对虾养殖基地进行黑鲷低盐度养殖试验,取得了良好的效果,现将2005年低盐度黑鲷鱼种培育试验报告如下。一、材料及方法1.池塘条件试验池塘是多年的对虾养殖池,面积为6.5亩,清整消毒是冬季伴随虾塘     

长毛对虾北移养殖初试

从浙江温州购进０．７ｃｍ长毛对虾苗１４万尾,暂养和盐度驯化后在５亩池塘养殖６３天,平均体长由１．２ｃｍ,增至８．４ｃｍ,旬增长１．１４ｃｍ。至９月底收获时,平均体长１０．５ｃｍ,亩产６２ｋｇ,亩效益６４０元。     

刀额新对虾对淡水的适应性观察

刀额新对虾原本生活于海水中，其人工育苗盐度一般为２５‰左右，要放养到淡水中养殖必须先经过一段时间的淡化，使其逐渐适应淡水环境，这是刀额新对虾淡水养殖成功与否的关键。现就该虾对淡水的适应性观察结果报告如下。一、材料与方法１．虾苗来源１９９８年５月１６日从厦门购进３００万尾规格为平均体长０．３ｃｍ的虾苗，测定海水盐度为２４‰。２．不同淡化速度观察经同等盐度暂养一天后，取１５０尾分成３组，１组和２组每６小时降低盐度２‰，３组每６小时降低盐度１‰，每隔２４小时计算一次存活数。每次换水后适量投喂丰年虫无节…     

南美白对虾池塘对淡养殖综合措施

一、前期准备１．虾池准备池塘要求水源充足，注排水方便，且注排水口分开，水质良好，虾池面积一般要求５～１０亩，池深１．５～２．５米，池埂坡度１∶（２～２．５）。每一个养殖周期开始前均须彻底清塘，清除池底污物和敌害生物，为对虾的栖息和生长营造一个良好的外部环境。２．纳水、配水和肥水在池塘一角用塑料薄膜围出约占整个池塘大小１／１０的面积，作为暂养淡化区。放苗前１０～１５天池塘进水５０厘米，在暂养区内投入一定量的日晒盐、氯化钾、氯化镁等氯化物，使暂养区水体盐度与苗场出苗池水盐度差小于１‰。配水结束后，利…     

池塘半封闭淡化养殖斑节对虾试验

探讨了在池塘条件下半封闭式淡化养殖斑节对虾的技术，成功地将斑节对虾养殖环境的盐度下限控制在1～2。通过培养基础饵料、科学驯养和使用微生物制剂等手段，使对虾的平均单产达到了3812kg／hm^2，产值达到10．8万元／hm^2。     

雨季养虾须预防应激

一、雨季引起对虾应激的原因1.盐度的变化南美白对虾放苗后逐渐降低池塘水体的盐度,有助于养殖的成功。但是,雨季,特别是雷阵雨、暴雨,常常出现对虾养殖池塘、近海的海水盐度急速下降。雨水是纯淡水,在无风、无增氧的状态,     

微生态制剂在甲壳动物养殖中的应用研究

在甲壳动物养殖中使用微生态制剂取得良好效果。南美白对虾室内养殖GMA1组、GMA2组及DY－1组的养殖成活率分别为95％．79％、91．78％和88．00％，均高于对照组的81．67％，微生物及水化学指标也明显优于对照组；池塘养殖中国对虾45d，试验组和对照组对虾平均体长分别增长2．86cm和2．40cm；河蟹育苗试验组比对照组提高成活率27．78％，本文还对微生态制剂的作用机理和使用注意项等进行了论述。     

多种鱼虾混养新模式

<正>目前对虾养殖的主要品种是南美白对虾。我们通过多年的对虾养殖研究工作,对不同的养殖模式进行试验分析,提出多种鱼与对虾混养,主养品种对虾,养殖过程少换水或不换水、一年一造的养殖模式,养殖三年,每年获得好效益。1.放苗前准备1.1池塘结构对虾养殖池1#号池8亩、2#号池10亩都为长方形钝角南北向,水深     

半滑舌鳎与中国对虾池塘混养技术

在半滑舌鳎养殖池中适当混养中国对虾,对虾可摄食鱼的残食,既节省饵料又改善池底环境,并可取得鱼、虾双丰收的成效,具有广阔的前景。1养殖池的选择1.1水源条件选择水源充足、潮流畅通、无污染,水质清新、悬浮物少、交通便利的地方;盐度在15‰～34‰。1.2养殖池条件进排水渠道分开,避免养殖用水污染;池塘无渗漏,池塘底质为沙底、沙泥底或泥沙底质为佳,利于鱼伏底潜沙。养殖池的规格以3～10亩为佳,也可利用现有的对虾养殖池进行改造;养殖池形状以长方形或长条形、平均水深以1.2m以上为好,设进排水闸门,进排水要流畅,排水时能将池水迅速全部排…     

南美白对虾白斑综合症病毒检测及其分析

用PCR方法对南美白对虾虾苗及养成期各阶段共613份样品进行了WSSV的检测，结果表明：在养殖各阶段南美白对虾均有WSSV的感染，虾苗的WSSV平均阳性比例为33．33％；养成期对虾的WSSV平均阳性比例为54．16％；水温27℃左右是南美白对虾最易感染WSSV的温度；海水养殖池对虾WSSV阳性比例远高于淡水池。     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.     

Imported ornamental fish are colonized with antibiotic‐resistant bacteria

There has been growing concern about the overuse of antibiotics in the ornamental fish industry and its possible effect on the increasing drug resistance in both commensal and pathogenic organisms in these fish. The aim of this study was to carry out an assessment of the diversity of bacteria, including pathogens, in ornamental fish species imported into North America and to assess their antibiotic resistance. Kidney samples were collected from 32 freshwater ornamental fish of various species, which arrived to an importing facility in Portland, Oregon from Colombia, Singapore and Florida. Sixty‐four unique bacterial colonies were isolated and identified by PCR using bacterial 16S primers and DNA sequencing. Multiple isolates were identified as bacteria with potential to cause disease in both fish and humans. The antibiotic resistance profile of each isolate was performed for nine different antibiotics. Among them, cefotaxime (16% resistance among isolates) was the antibiotic associated with more activity, while the least active was tetracycline (77% resistant). Knowing information about the diversity of bacteria in imported ornamental fish, as well as the resistance profiles for the bacteria will be useful in more effectively treating clinical infected fish, and also potential zoonoses in the future.     

Effect of iodophor disinfection of non‐hardened Salmo trutta eggs on their bacterial and fungus load

This study investigated the efficiency of iodophor disinfection (135 ppm active iodine for 15–30 min) of non‐hardened Salmo trutta eggs against different groups of bacteria and against fungus. Egg samples were taken from non‐disinfected and from disinfected eggs, microorganisms were cultured on specific nutrient media and their mass was measured by turbidimetric methods. Bacteria and fungus mass of non‐hardened eggs could be reduced but not eliminated by iodophor disinfection with 135 ppm active iodine for 15 min. The extent of reduction was 47–65% (Experiment 1). The efficiency of disinfection increased with disinfection time as the reduction in bacteria and fungus mass was 40–55% after 15 min and 58–74% after 30 min (Experiment 2). Disinfection efficiency of iodophor solution diluted in water (reduction 49–57%) and of iodophor solution diluted in sodium chloride solution iso‐osmolar to the oocytes (reduction 52–61%) was similar (Experiment 3). The reduction in bacteria and fungus mass was persistent as it was 39–72% lower in embryos deriving from disinfected eggs than in embryos deriving from non‐disinfected ones (Experiment 4). In conclusion, the tested disinfection method is inadequate to eliminate pathogens completely but it could positively influence immune defence of eggs and embryos.