史氏鲟南移驯养及生物学的研究: Ⅳ.稚鱼期小瓜虫病的治疗

在史氏鲟的南移驯养过程中, 其仔稚鱼阶段有多种病害发生, 尤以小瓜虫病最为常见和危害较大, 如不及时地控制会导致仔稚鱼的大量死亡。史氏鲟稚鱼小瓜虫病的防治方法与其它鱼类有很大的区别, 传统有效的治疗鱼类小瓜虫病的药物和方法不能用于史氏鲟稚鱼, 史氏鲟稚鱼对硝酸亚汞、孔雀石绿等传统的药物非常敏感, 这类药物不能用于治疗史氏鲟稚鱼的小瓜虫病。史氏鲟稚鱼对水温的变化也非常地敏感, 承受不了较大幅度的急速水温变化, 因此常用的快速变温治疗小瓜虫病的方法同样不能适用于史氏鲟稚鱼。实验筛选出以50ppm 的福尔马林溶液浸浴治疗史氏鲟稚鱼小瓜虫病是一种安全和有效的方法。     

岩原鲤小瓜虫病的防治

岩原鲤Procyprisrabaudi(Tchang)隶属鲤形目、鲤科、鲤亚科、原鲤属,俗称岩鲤、黑鲤鱼、墨鲤。分布于长江中上游及其支流,是一种栖居岩石缝间的底层鱼,为四川省重点保护鱼类之一。长期以来,岩原鲤成鱼大多依赖于江河捕捞,养殖中疾病较少,但小瓜虫病对鱼苗的危害一直较严重。现将笔者遇到该病的发生情     

一例岩原鲤小瓜虫病的诊治

<正>岩原鲤俗称岩鲤、墨鲤或水子，广泛栖息于水流缓慢、岩石较多的底层水体，是生活在长江上游和金沙江中下游的广温性鱼，其肌间刺少、肉质鲜嫩，具有较高的营养价值，深受消费者的青睐。随着岩原鲤人工繁殖技术成熟、规模化人工养殖技术的发展，由于养殖密度过大、生产过程中管理不当等因素导致岩原鲤病害频发，造成养殖效率低下，严重威胁到岩原鲤养殖业的健康发展。近日，重庆市荣昌区某养殖场暴发了一例岩原鲤的小瓜虫病，     

圆口铜鱼小瓜虫病的预防策略

<正>一、圆口铜鱼易感染小瓜虫病的主要原因1.生理特点淡水有鳞鱼中比较容易感染小瓜虫病的一些鱼,一般都有细小疏松的鳞片,如:圆口铜鱼、岩原鲤(幼鱼)、厚颌鲂等,而胭脂鱼、中华倒刺鲃、白甲鱼等鱼因为有紧密的鳞片保护,不容易寄生感染小瓜虫病。此外,圆口铜鱼丰富的皮下脂肪层或许更容易成为小瓜虫安居的"温床"。2.应激反应圆口铜鱼的驯养,业内公认有三个最主要的技术难点:应激反应、性腺发育及鱼病危害(主要是小瓜虫病)。笔者认为,应激反应与感染小瓜虫病之间存在一定的因果关系,即应激反应强的鱼类易感染小瓜虫病。容易引起圆口铜鱼应激反应     

虹鳟、金鳟苗小瓜虫病的中草药防治

小瓜虫病是对虹鳟、金鳟稚鱼危害较大的一种体表寄生性常见病和多发病,严重时常造成大批死亡。为实施无公害虹鳟、金鳟的养殖生产,我们在虹鳟、金鳟稚鱼培育期,试验总结出用辣椒 生姜和鱼虫克星(槟榔 苦楝)等中药浸洗防治小瓜虫病的有效方法,取得良好效果,现总结如下。     

浅议岩原鲤孵化方式的改进

<正>1.粘卵板式孵化岩原鲤产卵季节在每年的3-4月,水温18~26℃,14~16℃时也可以产卵,但产卵率、孵化率都较低。前些年岩原鲤苗种行情好,生产单位为了抢占市场,一般3月初水温不到14℃便开始起塘捕鱼,采用锅炉或电加热方式,为亲鱼暂养池(催产池)和孵化池升温。放流站2009年正式运行之初,岩原鲤成熟亲     

大西洋鲑稚鱼（Oncorhynchus solar）小瓜虫病（Lchthyophthirius filiis）的防治试验

给大西洋鲑稚鱼造成直接危害是小瓜虫的营养体，用500ppm的36%甲醛溶液和5ppm的孔雀石绿药浴30分钟，每隔2天进行一次药浴，连续三次，取得100%杀灭寄生于体表与鳍条上小瓜虫，建议预防性用药浓度250ppm福尔马林，2ppm孔雀石绿止水消毒60分钟，每隔15天对稚鱼进行预防性消毒，避免造成稚鱼批量死亡的后果，特别注意在雨天过后，即开始进行预防性消毒，将会取得事半功倍的效果。     

鲤鱼养殖技术之二 岩原鲤池塘育种技术

岩原鲤[Procypris rabaudi(T.chang)]隶属于鲤亚科,原鲤属,是长江上游名贵经济鱼类,仅分布于长江三峡以上干、支流,其分布区狭窄.岩原鲤以前只作为天然渔获物,未能进行人工养殖,因此,种群数量越来越小,近几年才开始进行人工养殖试验.重庆市万州区水产研究所于2002年5月10日～7月2日进行了岩原鲤鱼种的池塘培育,现将试验情况报告如下.     

人工养殖条件下岩原鲤幼鱼排空率与摄食量

在室内微流水养殖条件下,以水蚯蚓(Limnodrilus sp.)为饵料,应用现场胃含物法,研究岩原鲤[Procypris rabaudi(Tchang)]幼鱼的排空率和日摄食量。结果表明:岩原鲤幼鱼摄食强度具有明显的昼夜节律,呈现较典型的单峰分布特征,其摄食强度高峰时间在0:30到6:30;在实验水温18.6℃时,用湿重表示胃含物质量,线性、指数和平方根3种常用模型均可较好拟合岩原鲤幼鱼[体质量(3.30±0.94)g]的排空率实验数据(df=18,P<0.001),综合评价结果进一步表明,其中指数模型拟合度最好,所得模型为St=0.139e-0.169t(r2=0.952,P<0.001);同时得到岩原鲤幼鱼的排空率(以湿重计)为0.169 g/(100g.h)。实验得到养殖岩原鲤幼鱼的日摄食量(湿重)为24.91 g/(100g.d);应用Elliott-Persson模型评估得到自然环境中岩原鲤幼鱼日摄食量(以湿重计)Cd=14.309 g/(100g.d)。研究建立的岩原鲤幼鱼空消化道重(EDW)-体长(BL)-体质量(BW)经验关系式为EDW=0.24(BW/BL)1.547-0.139(n=83,r2=0.89)。研究表明,指数模型最适于描述岩原鲤幼鱼胃排空特征,Flliott-Persson模型在野外环境中岩原鲤幼鱼摄食评估上具有较大适用性。这些结果可为岩原鲤幼鱼摄食生态的定量研究及环境容纳量评估提供基础资料。     

鱼类小瓜虫病免疫研究进展

小瓜虫病是淡水鱼类和观赏鱼类的一种常见寄生虫病。鱼感染小瓜虫后，在血清和体表黏液中产生抗体，这种抗体主要是鱼受到小瓜虫体细胞表面膜蛋白的刺激，通过血液和体表黏液中淋巴细胞产生出来的，以阻止小瓜虫的运动并杀死虫体。目前还没有正式用于生产的小瓜虫疫苗，但实验室疫苗已研制成功，包括经冷冻和福尔马林处理后的死疫苗、小瓜虫活疫茁以及小瓜虫基因疫苗等。综述了，多年来小瓜虫病的免疫研究概况、鱼类对小瓜虫免疫反应类型、反应机制以及抗小瓜虫疫苗等。     

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.     

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.     

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.