网箱养殖罗非鱼突发肠炎病的治疗

网箱养殖罗非鱼突发肠炎病的治疗１９９４年河北省抚宁县洋河水库内网箱养殖的１０８箱罗非鱼（网箱规格为５ｍ×５ｍ×２．５ｍ，每箱投放５０～７５ｇ／尾的罗非鱼种３００～３５０ｋｇ）于７月下旬患突发性肠炎病。每天每箱死鱼７～８尾，到８月１０日，每箱死鱼达６０...     

微型网箱养殖黄鳝技术研究

利用４只微型网箱及附设的人工寄居巢、食台、遮蔽物等属具，以每ｍ２放养尾均重１６．６ｇ、２０．８ｇ的黄鳝种３．２５～７．２７ｋｇ，通过药饵驱虫、投喂螺、蚯蚓浆配合饲料，观测并及时用光合细菌等调节水质及防治鳝病等技术措施，经９７和１２６ｄ的养殖试验研究，每ｍ２网箱平均毛产尾均重５６．９ｇ的黄鳝１４．５１ｋｇ，净产９．４９ｋｇ，成活率９１．９％，生长指标９．４２６８。研究初步说明网箱养鳝模式简便易行，每ｍ２放养尾均重２０ｇ．左右的鳝种４．０～４．７ｋｇ效果较好。     

网箱高密度养殖斑点叉尾鱼回试验

斑点叉尾鱼回是美国水产养殖的优良品种，我省开展其小体积高密度网箱养殖始于１９９５年，１９９７年进行了较大面积试验推广。我们在山仔水库使用小网箱５０只，在２００ｍ３水体中投放鱼种５５９９７尾，尾均重１４３ｇ，平均每箱放养１１２０尾。经过７个月的养殖，...     

再循环水池中的斑点叉尾Hui养殖

为了提高鱼池斑点叉尾Ｈｕｉ的养殖产量，作者在０．０４ｈａ的土质鱼池中，通过使成离心泵（２２７升／分）将底部池水陆列表层的方式，做了３次再循环水养殖研究，其中有２次研究抽取的池水通过１０００升的生物过滤器进行了处理。放养鱼种平均规格４５ｇ／尾，放养密度７４１０尾／ｈａ至１９７６０尾／ｈａ到１０６０１ｋｇ／ｈａ，商品鱼规格４５０ｇ以上，其中研究３中的一口鱼池产量最高为１３３８７ｋｇ／ｈａ。研究表明，再     

南方大口鲶苗种的选购与放养

南方大口鲶肉质细嫩，味道鲜美，养殖周期短，养殖利润是常规品种的３～６倍，深受养殖户和消费者喜爱。但是，一些缺乏经验的养殖户，由于种种原因，购进的南方大口鲶苗种成活率普遍偏低，使得部分养殖户遭受损失。笔者根据这几年的实践，将有关技术措施总结如下：１谨慎选购 一种是杂交型的大口鲶，其母本（属近亲繁殖）体重 ２． ５ ｋｇ左右，父本（土鲶、小口鲶）为本地鲶，体重 ３００～５００ ｇ，养殖 ２００天后，尾重在 ５００ ｇ以上。一种是本地鲶，父、母本纯属本地鲶，亲本体重２００～５００ ｇ，苗种养殖 ２００天后，尾重…     

俄罗斯鲟南移人工养殖试验

１９９９年７月从北京引进俄罗斯鲟鱼苗种在广西水产学校名特优水产实验场（武鸣基地）进行了南移人工养殖实验，在室外水泥池中投放鲟鱼苗４５００尾，平均体长为７ｃｍ（５～１０ｃｍ），经１５３ｄ饲养，得鲟鱼种３１５０尾，平均体长为３７．８ｃｍ，均重２１５ｇ。其中最大个体体长为５０ｃｍ，体重３７８ｇ，养殖成活率为７０％。     

池塘主养淡水白鲳放养密度试验

在３口０．８３亩池塘进行主养淡水白鲳的密度试验，分别放养平均尾重１４５ｇ鱼种５６０尾、９４０尾、７２５尾、并混养鲢、鳙、鲤、罗非鱼。结果：３口池塘分别折合每亩净产１２０６．２８ｋｇ，１３９２．０６ｋｇ，１０４３．４１ｋｇ，每亩纯收入６０００元左右。在盐度为１０的池塘中，养殖淡水白鲳，平均日增重６．７ｇ。     

网箱养殖云南高背鲫及异育银鲫试验

网箱养殖高背鲫及异育银鲫，投喂颗粒饲料。高背鲫单产１８４６ｋｇ／ｍ２，规格１６２ｇ／尾，增重倍数３０８；异育银鲫大网箱单产２０６８—２２３６ｋｇ／ｍ２，规格１７８—１８１５ｇ／尾，增重倍数３１３—３４５；异育银鲫小网箱单产１０８—１６７ｋｇ／ｍ２，规格１７２—１８６ｇ／尾，增重倍数３３４—４３２。     

池养黄鳝生长速度的观测

平均放养密度为３ｋｇ／ｍ２（尾重２１ｇ，全长３０ｃｍ），顺水泥池内以泥垅打洞作寄身巢的黄鳝，经９６ｄ的人工强化养殖，其生长比速为０．９６４４，生长指标为２８．９；平均增重率２７４．９％，平均每尾净增重５７．７ｇ，单产８．８ｋｇ／ｍ２。该结果初步表明，水泥池中强化养殖的黄鳝，生长速度远快于规格相近、在自然水域中生长的黄鳝．     

斑点叉尾鮰实用养殖技术（六）──鱼病防治

斑点叉尾鮰实用养殖技术（六）──鱼病防治斑点叉尾鮰的鱼病防治是养殖过程中的一个重要环节，尤其在高密度养殖中显得突出，必须坚持“无病先防、有病早治、防重于治”的方针，切实落实好防病治病的措施。一、病毒性疾病病原：斑点叉尾病毒（ＣＣＶＤ）病状：病鱼皮肤及...     

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).     

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.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.