淡水蓝鲨疖疮病及防治

近年天津市观赏鱼养殖品种呈现多样化发展,新的观赏鱼品种淡水蓝鲨落户津城,津郊养殖、暂养该品种的养殖户渐多,经济效益可观。淡水鲨鱼为热带性鱼类,色彩鲜艳,也可作观赏鱼养殖。目前由于养殖密度高、管理不善、防病治病措施不力等原因,养殖期间病害易暴发流行,给养殖户造成较     

淡水鲨鱼养殖技术

淡水鲨鱼又称苏氏圆腹（鱼芒）、虎头鲨、巴丁鱼或八珍鱼,主要分布在东南亚一带,为近年新引进的淡水优良品种。 一、生物学特征 1.体型与体色。淡水鲨鱼体色有黑、白、灰、红四种。前三种体色的鲨鱼多作为食用鱼饲养,尤其是灰鲨鱼最受欢迎,其背部青色,体侧青灰色,腹部银白色;红鲨鱼即水晶巴丁鱼,多作观赏鱼饲养。 2.适应性与食性。淡水鲨鱼耐低氧能力强,适应性广,但抗低温能力较弱。适温20℃-34℃,最佳生长水温26℃-32℃,     

广东梅州市梅县区成功试养淡水鲨鱼

<正>2014年10月,梅县区试养淡水鲨鱼获得成功。随着养殖规模的不断扩大,淡水鲨鱼有望成为当地一个新兴养殖品种。为了发展渔业生产,梅县区畜牧兽医水产局引导水产专业户引进试养淡水鲨鱼,开展苗种培育和成鱼养殖。目前,已有淡水鲨鱼成鱼养殖水面3 000亩以上,供苗能力3 000万尾水平。据了解,淡水鲨鱼生长快、个体大、食性广、耐低氧、易饲养,而且养殖病害少、产量高,亩产超过     

淡水鲨鱼微流水池塘健康养殖试验

淡水鲨鱼(图见彩中插2),俗称八珍鱼、虎头鲨、巴丁鱼,为淡水名贵鱼类。主要分布在东南亚一带,原产于马来西亚、泰国等地,是东南亚国家的重要经济鱼类。广西水产引育种中心在2004年淡水鲨鱼人工繁殖成功和几年产研突破的基础上,2008年进行了微流水淡水鲨鱼健康养殖试验,取得了显著的效益。现将结果报告如下。     

淡水鲨鱼池塘混养试验

淡水鲨鱼（Pangasius sutchi）又称苏氏圆腹芒、虎头鲨、巴丁鱼或八珍鱼，主要分布在东南亚一带，为近年我国新引进的淡水优良品种。为本文介绍了池塘混养淡水鲨鱼的试验情况。     

淡水鲨鱼池塘养殖高产试验

淡水鲨鱼（Pangasius utchi Fowier）．隶属于鲶形目，鱼芒鲶科。原产于东南亚的泰国、老挝、柬埔寨、越南等地，适宜的生长水温为22—32℃。该鱼肌间刺少．肉质细嫩．营养价值高，并具有生长快、食性杂、耐低氧、病害少、适应性强等优点，深受人们的喜爱。为尽快发展淡水鲨鱼这一优良品种。山东省海洋与渔业厅于2003年下达了“淡水鲨鱼池塘高产养成技术研究”项目。2004年．我们进行了淡水鲨鱼池塘高产养成试验．现将养殖试验情况报告如下。     

淡水鲨鱼工厂化温流水养殖试验

为了探索淡水鲨鱼工厂化温流水养殖技术,我站于2002年10月在彭城电厂进行了淡水鲨鱼温流水养殖试验,获得了较好的效果.现将试验情况报告如下:     

几种名优水产品养殖技术简介

从去年开始,北京市水产技术推广站陆续为我市郊区渔场引进了如淡水鲨鱼等名优水产养殖品种,这些品种刚刚引进我市,因此在这里简单介绍一下它们的养殖技术,供广大养殖户参考。 一、淡水鲨鱼:淡水鲨鱼隶属芒科、芒属,是苏氏园腹芒(Pangasius Sutchi)的俗称,主要分布于东南亚一带,有黑、白、灰三种体     

热带地区池塘工程化循环水模式下淡水鲨鱼的试验养殖及养殖密度对其生长性能的影响

正为了验证热带地区应用池塘工程化循环水模式养殖淡水鲨鱼的可行性,同时初步探究不同养殖密度对淡水鲨鱼生长性能的影响,本试验设置了30000尾/槽和40000尾/槽2个养殖密度,经过120d的试验养殖,其结果显示:低密度槽淡水鲨鱼在各个阶段的体重及体长增长量、体重增重率(WGR)、特定生长率(SGR)和绝对生长率(AGR)均高于或等于高密度槽,显现出在池塘工程化循环水养殖模式下,相对高的养殖密度会对淡水鲨鱼的生长性能产生负影响。     

淡水鲨与花白鲢混养技术初探

淡水鲨鱼学名苏氏圆腹鱼芒(Pangasius sutchiFowier),又称虎头鲨、巴丁鱼或八珍鱼,隶属鲶形目,鱼芒鲶科,主要分布在东南亚一带,是马来西亚、泰国等地区的优良淡水鱼类。淡水鲨鱼体色有黑、白、灰、红4种,前3种体色的鲨鱼多作为食用鱼饲养,尤其是灰鲨鱼最受欢迎,其背部青色,体侧     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

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.     

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.     

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).