七种养殖特色淡水鱼脏器系数的测定和比较

为研究养殖特色淡水鱼成鱼主要脏器系数,并探讨各品种组织器官重量与体重的关系,本研究对杂交鲟(俄罗斯鲟Acipenser gueldenstaedti♀×史氏鲟A.schrenckii♂)、斑点叉尾(鮰)(Ietalurus punetaus)、鳜(Siniperca chuatsi)、大口黑鲈(Micropterus ...     

6种鲟鱼鱼皮营养评价与组织学分析

以西伯利亚鲟、俄罗斯鲟、达氏鳇、欧洲鳇、大型杂交鲟(达氏鳇♀×史氏鲟♂)以及小型杂交鲟(西伯利亚鲟♀×史氏鲟♂)的鱼皮为研究对象,对其基本营养成分、矿物质含量、氨基酸和脂肪酸组成以及组织学特性进行分析,比较和评价这6种鲟鱼鱼皮营养成分和组织学特性的异同。试验结果显示,6种鲟鱼鱼皮中均富含胶原蛋白(21.85%～30.47%),且呈味氨基酸所占比例高达52.19%～53.04%,脂肪酸和矿物质元素种类丰富。欧洲鳇的粗蛋白含量(37.21%)最高;达氏鳇的不饱和脂肪酸含量(27 287.63μg/g)最高且呈味氨基酸占比(53.04%)最高;俄罗斯鲟的矿物质元素含量丰富,其中钙元素含量(18 101.08 mg/kg)最高。组织学分析表明,达氏鳇、欧洲鳇及大型杂交鲟的胶原纤维束紧密粗大,而西伯利亚鲟、俄罗斯鲟和小型杂交鲟的胶原纤维束细小疏松。试验结果可为促进鲟鱼鱼皮的高值化利用和开发应用提供科学依据。     

冷泉水养殖条件下的史氏鲟和杂交鲟鱼种的饲养试验

在冷泉水养殖条件下进行史氏鲟和杂交鲟(史氏鲟♀×西伯利亚鲟♂)鱼种的饲养试验,史氏鲟和杂交鲟鱼种的平均体重分别为(2.51±0.57)g和(2.16±0.33)g;平均全长分别为(6.55±0.69)cm和(6.11±0.33)cm;试验期水温为18~22℃。经70 d人工培育,投喂含48%粗蛋白的人工配合饲料,史氏鲟和杂交鲟鱼种的平均体重分别达到(22.25±5.53)g和(26.19±6.16)g,平均全长分别达到(13.87±0.61)cm和(14.17±0.77)cm。杂交鲟鱼种平均体重和平均全长特定生长率均高于史氏鲟。以Bertalanffy非线性生长模型算得的史氏鲟和杂交鲟鱼种体重生长拐点分别为67 d和71 d,全长生长拐点日龄分别为30 d与33 d;全长生长拐点的出现先于体重拐点;杂交鲟鱼种体重和全长生长拐点比史氏鲟鱼种分别推迟4 d和3 d,杂交鲟鱼种全长生长增速持续时间大于史氏鲟鱼种。     

三种鲟鱼的盐度驯化试验

通过连续递增盐度和阶段性递增盐度对史氏鲟、达氏鲟和杂交鲟(达氏鲟♀×史氏鲟♂)三种鲟鱼进行盐度试验,结果表明:采用阶段性递增盐度对史氏鲟和杂交鲟进行驯化,最终达到海域盐度(3 0‰),其死亡率分别为6.7%、3.3%和5.0%,对鲟鱼进行盐度驯化切实可行.     

重庆山区4种鲟仔、稚、幼鱼生长特性对比研究

为有效筛选出适宜重庆山区养殖的鲟鱼品种,将卵黄囊消失的施氏鲟、西杂鲟(西伯利亚鲟♀×施氏鲟♂)、施杂鲟(施氏鲟♀×西伯利亚鲟♂)、大杂交鲟(达氏鳇♀×施氏鲟♂)仔鱼饲养在直径2 m、高0.6 m的蓝色圆形玻璃钢盆中,每盆3000尾,开始时投喂打碎的水蚯蚓,7 d后(全长约3 cm),用微粒饲料与水蚯蚓浆制成软颗粒饲料,阴干后投喂,经15～20 d转食后,投喂鲟鱼专用微粒饲料,养殖84 d后比较分析4种鲟鱼胚后发育时间,形态特征,及仔、稚、幼鱼成活率、生长特性等。试验结果显示：在水温(17.94±0.54)℃、溶解氧质量浓度(8.91±0.32) mg/L、pH(8.09±0.43)的条件下,大杂交鲟、西杂鲟胚后发育时间早于施杂鲟和施氏鲟;4种鲟幼鱼外部形态特征均有区别;西杂鲟成活率最高,为(65.33±2.12)%,显著高于施氏鲟、施杂鲟和大杂交鲟;7日龄后,4种鲟鱼特定生长率随着日龄增加而降低;从生长模型可知,西杂鲟全长生长速度最快,从(0.81±0.34) cm增长至(16.67±1.37) cm,大杂交鲟体质量生长速度较快,西杂鲟次之,但77日龄后西杂鲟体质量生长速度超过大杂交鲟...     

鲟鱼的营养需求与仔鱼投饵技术

我国人工养殖的鲟鱼主要是原产于黑龙江的史氏鲟、杂交鲟及引自俄罗斯的优良品种———俄罗斯鲟、闪光鲟和小体鲟。一、鲟鱼的营养要求１．蛋白质许多学者的研究结果表示，不同种类的鲟鱼对饲料中蛋白质的需求比较接近。高首鲟（体重１４５～３００克）的饲料蛋白含量的适宜范围为３６．５％～４０．５％，最高增重率需求为４９．６％，用Bro－kenlinemodel确定，饲料中蛋白质最适含量为４０．５％±１．６％。西伯利亚鲟（体重２２～４７克）饲料蛋白质的最适含量为４０％±２％，最高增重率需求为４９％。史氏鲟仔鲟的饵料中粗蛋白含量以…     

基于杂交鲟幼鱼生长性能、体成分和血清生化指标的鲟饲料养殖效果分析

为进一步了解和评估国内鲟饲料的状况和养殖效果,本实验在前期研究基础上筛选了4种品质达标、价格一致的鲟饲料.以杂交鲟(Acipenser baerii♀×A.schrenckii♂)作为养殖对象进行8周的养殖实验,对比分析4种鲟饲料养殖效果.将240尾初始体重为(512.48±3.10)g的杂交鲟幼鱼按投喂饲料品牌分为4...     

史氏鲟、西伯利亚鲟及其杂交种群体生化遗传学分析

采用聚丙烯酰胺凝胶电泳法对史氏鲟、西伯利亚鲟及其正、反杂交种[即史氏鲟(♀)×西伯利亚鲟(♂)杂交种、史氏鲟(♂)×西伯利亚鲟(♀)杂交种]4个群体进行了9种同工酶表达分析。结果表明,史氏鲟的多态位点比例最低(20.00%),西伯利亚鲟及史氏鲟(♂)×西伯利亚鲟(♀)杂交种的多态位点比例最高,且相等(35.00%);群体平均杂合度期望值为0.1215～0.1744;聚类分析表明,史氏鲟、史氏鲟(♀)×西伯利亚鲟(♂)杂交种聚为同一分支,西伯利亚鲟、史氏鲟(♂)×西伯利亚鲟(♀)杂交种聚为另一分支。     

西伯利亚鲟与杂交鲟苗种培育对比试验

<正>西伯利亚鲟是引自欧洲的鲟鱼种类,是目前世界上养殖最广泛的鲟鱼种类,施氏鲟是原产于黑龙江的鲟鱼类,是目前国内养殖范围仅次于西伯利亚鲟的种类,在长期的养殖实践中发现这两种鲟鱼都有自身的劣势,如西伯利亚鲟不耐高温而施氏鲟不耐运输,同时,国内的杂交鲟种类不断增加,一些是从国外直接引进的,一些是国内生产的,这些杂交种的养殖效果差距较大,因此本文进行了西伯利亚鲟和杂交鲟(西伯利亚鲟♀×施氏鲟♂)苗种培育的比较。     

饲喂枯草芽孢杆菌对杂交鲟生长和肠道菌群结构的影响

枯草芽孢杆菌(Bacillus subtilis)(Gutcare?,DSM32315)按0.00％(对照组)、0.10％、0.20％和0.40％的浓度添加到饲料中,投喂杂交鲟(西伯利亚鲟Acipenser baerii♀ ×施氏鲟A.schrenckii♂)90 d,通过观察其对杂交鲟幼鱼生长性能、血液理化指标和肠道...     

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.