不同温度条件对鳜仔鱼摄食和生长发育的影响_

鳜（Ｓｉｎｉｐｅｒｃａｃｈｕａｔｓｉ）又称季花鱼、桂鱼,属鲈形目（Ｐｅｒｃｉｆｏｒｍｅｓ）科（Ｓｅｒａｎｉｄａｅ）主要分布于我国东部。其肉嫩味美,为淡水鱼类中珍品,鉴于鳜本身的价值以及在人工养殖中尤其是鱼苗繁育过程中的高死亡率,对鳜的研究也陆续见诸...     

香港的巨大市场促进其水产养殖业的发展

在香港,由于对活鱼的需求量很大,因此池塘养鱼获利不小。池塘所产之鱼几乎全以活鱼形式投放市场。目前,香港新界的池塘养殖产量只能满足当地对淡水鱼需求量的15%。据最近统计,香港大约开发了1,890公顷鱼池,还有260公顷面积正闲置未开,准备填土建筑房屋。香港池塘养鱼主要采用三种方式:混养、鱼—鸭综合养殖和单养。混养是主要的养殖方式,约占香港池塘     

养殖鲟鱼非寄生性疾病的诊断与控制

鲟鳇鱼养殖已在我国悄然兴起,养殖品种有施氏鲟(ＡｃｉｐｅｎｓｅｒｓｃｈｒｅｎｃｋｉｉＢｒａｎｄｔ)、达氏鳇(Ｈｕｓｏｄａｕｒｉｃｕｓ)、俄罗斯鲟(ＡｇｕｅｌｄｅｎｓｔａｅｄｔｉＢｒａｎｄｔ)、杂交鲟(ｂｅｓｔｅｒ)等。从当前情况看,养殖杂交鲟、俄罗斯鲟、施氏鲟效果较好。鲟鳇鱼类生长快、抗病力强的特点已被国内外养殖者公认,但在集约化养殖条件下,出现较多非寄生性疾病。高首鲟(Ａｔｒａｎｓｍｏｎｔａｎｕｓ)脂肪织炎、施氏鲟肝性脑病和鲟鱼心外膜脓肿均属非寄生性疾病,为鲟鱼养殖的主要疾病,虽然这些疾病无传染性,但就高度集…     

水晶巴丁鱼养殖技术

水晶巴丁鱼学名苏氏圆腹　（Ｐａｎｇａｓｉｕｓ　Ｓｕｔｃｈｉ），原产于马亚西亚、泰国等地的江河、湖泊中，是东南亚国家重要的养殖优良品种，也是人们喜爱的垂钓对象，有黑、白二种体色，黑色俗称淡水青鲨；白色俗称淡水白鲨。水晶巴丁鱼外观美丽，其肉味鲜美，无小刺，被东南亚国家和香港视为名贵食用鱼。我们在２０００年对水晶巴丁鱼进行了引种养殖，效果很好，现将有关养殖技术介绍如下：一、生物学特性形态特征：该鱼体长，侧扁，背部隆起，具脂鳍，头部扁平呈圆锥形，吻短，口亚下位，鳃膜与颊部不相连，外形似鲨鱼。生活习性：喜…     

海南海水网箱养殖石斑鱼经济技术调查

海南省海水网箱养殖石斑鱼经过4年时间的试验与推广,在一些市县已形成了群众性的养殖热,并已发展成为具有相当规模的网箱养殖出口商品基地。发展经过与现状海水网箱养殖石斑鱼始于1984年9月,由香港新源兴水产有限公司与陵水县经济发展公司、陵水县新村镇合作,在陵水县新村港帅先养殖。当时从香港引进54口网箱,从菲律宾、福     

香港渔业

香港的渔业由捕捞、海鱼养殖及塘鱼养殖组成。捕捞渔业及海鱼养殖业的产量约占香港海鲜食用量的26％，而塘鱼养殖业的产量约占淡水鱼食用量的5％。近年来．香港渔业规模不断萎缩，渔民生存空间越来越窄。     

评《Culture and Capture of Fish Chinese Reservoirs》

评《ＣｕｌｔｕｒｅａｎｄＣａｐｔｕｒｅｏｆ　ＦｉｓｈＣｈｉｎｅｓｅ　ｅｓｅｒｖｏｉｒｓ》中国是世界上淡水养殖产量最高的国家，但目前向国外介绍的有关鱼类养殖技术的文献基本上限于池塘养殖。根据预测，亚洲及世界各地将大力兴建水库，水库渔业将具有很大的发展潜...     

中华绒螯蟹1种球状病毒颗粒的电镜观察

中华绒螯蟹(Ｅｒｉｏｃｈｅｉｒｓｉｎｅｎｓｉｓ)养殖病害问题已成为制约养殖生产的主要因素,病害造成的损失逐年增长,损失也越来越严重。1996年以来,江苏、浙江、安徽等地相继发生养殖中华绒螯蟹患颤抖病成批死亡的病例,养殖单位采用多种抗菌药物治疗均无明显效果。病蟹...     

刀额新对虾Metapenaeus ensis（de Hann）淡水池塘养殖技术措施

刀额新对虾Ｍｅｔａｐｅｎａｅｕｓ ｅｎｓｉｓ（ｄｅ Ｈａｎｎ）是近几年发展的新的养殖对象。本文作者总结刀额新对虾淡水池塘养殖的关键技术措施，以飨读者，以便推广。     

国外简讯

国外简讯鲈鱼的养殖经营方式与经济效益美国养殖一种杂交鲈鱼，是由金鼠狼鲈（Ｍｏｒｏｎｅｃｈｒｙｓｏｐｓ（♂）与美洲狼鲈（Ｍｏｒｏｎｅｓａｘａｔｉｌｉｓ（♀）杂交而成。这种杂交鲈鱼生长快、抗病力强、对盐度适应范围广、耐低温，因而受到养殖业者的欢迎。养殖鲈...     

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.