两栖鱼的秘密

鱼类有海水鱼和淡水鱼之分，它们只能分别栖息生活在海水或淡水之中，但有些“两栖”鱼类如鲈鱼、鳗鲡、鳆鱼(鲍鱼)、马哈鱼等都可生活在淡水中，又可邀游在海水里。     

鱼类珍闻奇趣录

<正> 两栖鱼 这里所说的两栖,不是水陆两栖,而是海水和淡水两栖的鱼。本来生活在淡水的鱼,无法忍受和抵抗海水中盐分的侵袭,但是生活在海水的鱼,尽管吞吐大量的海水,却不怕海水的苦咸,依然逍遥自在。这是什么道理呢?原来是在海水鱼的鳃片里有一种能排除盐分的特殊组织,叫做氯化物分泌细胞。     

尼罗罗非鱼在淡水和海水中的生长及对蛋白质需求的比较

以酪蛋白为蛋白源,配制蛋白质含量为19 80%～40 50%的6种精饲料,采用室内循环水养殖系统,在饱食投喂和(27±1)℃水温条件下对吉富品系尼罗罗非鱼幼鱼进行8周的饲养实验,比较其在淡水和海水中的生长及蛋白质需求。结果显示:尼罗罗非鱼在淡水和海水中生长良好,存活率分别为100%和87%～100%;随着饲料蛋白质含量增加,实验鱼的平均终重、增重率和日增重率呈线性增加,饲料系数呈线性下降,蛋白质效率也呈下降趋势。在相同的饲料蛋白水平下,上述指标在淡水鱼和海水鱼之间均无显著差异蛋白质适宜需要量为28%～32%。     

怎样进行鱼类两栖类的保活运输与保活储存──附谈HY与SW系列多功能活鱼运输机组的使用需知

（上接本刊1997年第4期）实验后的结论如下1、绝大多数的海水鱼类，都能由HY系列多功能活鱼运输机组进行保活长途运输。其成活率与一般淡水鱼类相接近：在90％至98．8％之间，有些品种甚至能达到100％成活。2、海水鱼类的能载密度也和淡水鱼类相近，鱼：水可达1：1左右。而原习惯认为最难运输的鲸鱼、其能载密度甚至还可高达鱼：水一1．5：l3、海水鱼类的运距（由甲地至乙地的距离），亦接近淡水鱼。一般可达到1000km至2000km之间。4、运时（启动至终运间的耗时）约达36～100小时。5、海水鱼类保活长途运输的技术要求：L适运水温：10C～26…     

赤点石斑鱼Epinephelus akaara(Temminck et Schlegel)鱼怪病(Ichthyoxeniosis)的防治研究

本文扼要介绍了赤点石斑鱼鱼怪病的发病情况，症状与药物试验结果，并就淡水鱼怪病与海水鱼怪病的治疗方法进行比较，结果发现，淡水鱼的治疗方法对石斑鱼并不适用，甲醛试剂对石斑鱼鱼怪病的治疗比较有效。     

两种冷冻淡水水产加工品的制作工艺

淡水鱼以往一直是鲜活食用的，由于淡水鱼死后或冷冻后蛋白质发生冷冻变性及其他生化变化，其口感和风味下降程度严重，这点和海水鱼不太相同，所以传统上极少有冷冻产品。近几年来，随着我国淡水水产品养殖业的发展和水产加工技术的日益进步，逐步开拓淡水水产品冷冻品及冷冻调理食品的加工，不仅可解决旺     

近红外光谱技术在鱼糜定性和定量上的应用

以海水鱼糜(包括狭鳕、带鱼、鲷和混合鱼糜)以及淡水鱼糜(包括鲢和草鱼鱼糜)为研究对象,应用傅立叶近红外光谱技术结合化学计量学对鱼糜进行定性和定量分析。用聚类分析和线性判别的方法建立海水和淡水鱼糜的定性鉴别模型,并应用偏最小二乘法(PLS)分别建立海水鱼糜水分含量和蛋白质含量的近红外定量分析模型。结果表明,海水和淡水鱼糜的定性鉴别模型预测率达100%;建立的近红外定量分析模型中,海水鱼糜的水分和蛋白质的模型的相关系数分别达0.98和0.96以上,模型能较为准确、快速地预测定海水鱼糜中水分和蛋白质含量,有很大的潜力可应用于实际生产。     

鱼类的淋巴囊肿病

淋巴囊肿病据外观病状即可进行诊断，是发现最早的鱼类病毒性疾病之一，于1874年就有记载，也是最早有文字记载的鱼类病毒病，目前国外曾报告包括海水、淡水和半咸淡水在内的9科42目125种鱼类患淋巴囊肿病。在淡水鱼上主要是危害丽科的鱼，如各种慈鲷和短鲷；海水鱼类有鲈形目、鲽形目和纯形目中的一些种类。     

嘉兴秀洲区即食淡水鱼加工初探

<正>随着养殖技术的不断提高,嘉兴秀洲区淡水养殖业不断发展,淡水养殖产量稳定上升。但同时由于产后加工技术和水产品市场建设相对滞后,导致渔业生产效益相对下降,农民的生产积极性不高,严重影响了淡水养殖业的进一步发展。淡水鱼骨刺多,泥土味浓,由于饮食习惯的原因,一直不被国内外加工业重视。秀洲区淡水鱼以活鱼鲜销为主,淡水鱼加工比例低,产品较少,除了冷冻切割鱼段等半成品加工外,以传统淡水鱼加工制品为主。由于加工设备简陋、技术落后,且多采用作坊式加工,产品质量不稳定,保质期短,难以形成工业化生产。嘉兴秀洲区与浙江工商大学合作开发淡水鱼深加     

加入WTO对我国渔业的影响及其对策^（续）

2.大力发展水产品精深加工:发展淡水产品加工的方法和方向:①保活。推广高新技术的新型活鱼车、活鱼船、集装箱,搞好活鱼运输,以适应市场需要。②保鲜。采用冰鲜、微冻、冷冻等低温技术,对淡水产品进行流通保鲜运销、而且也为淡水产品的深加工提供了可靠的质量保证。③发展冷冻产品加工。目前,我国淡水冷冻产品主要有以下几种:冷冻小包装、冻鱼片、冻鳝片、冻银鱼、冻小杂鱼、冻田螺肉、冻熟虾仁、冻虾仁、冻虾、冻整鱼、冻鳗鱼等,这些产品不仅解决了由于淡水产品季节性特点形成的滞销,丰富了市场,而且能出口创汇,是目前我国大力发展水产品加工的重要途径之一。     

Particularities of early life stages in temperate freshwater fish species: comparisons with marine species and implications for aquaculture practices

Both egg and larvae are different between freshwater and marine fish species. Freshwater fish species have generally larger and fewer eggs than marine species. Most freshwater fish species have demersal eggs that develop stuck to various substrata, such as plants or gravels, while eggs of most marine fish species develop in the water column. These differences have consequences for both the evaluation of the quality and the incubation of eggs of freshwater fish species compared with marine species. The larvae of many freshwater fish species are larger and more developed at hatching than their marine counterparts: thus, larval feeding regimes could be different and cannibalism may emerge sooner in certain freshwater fish species. The main differences of egg and larvae between freshwater and marine species are highlighted and the possible implications for aquaculture practices are discussed.     

冬夏两季五种经济鱼类组织脂肪酸含量及组成分析

为了解不同季节不同鱼类不同组织中的不同脂肪酸含量,科学地指导鱼类膳食消费,本实验研究了冬夏两季,采集自上海市场常见的5种经济鱼类:大黄鱼(海洋肉食性),银鲳(海洋杂食性),日本鳗鲡(淡水肉食性),莫桑比克罗非鱼(淡水杂食性),草鱼(淡水草食性),分别检测鱼背部肌肉、腹部肌肉、尾部肌肉、肝脏和腹腔脂肪组织的脂肪含量和脂肪酸绝对含量。结果显示,5种鱼肌肉脂肪酸谱存在显著差异,并与各自的生活环境及食性均有关系;在鱼的腹腔脂肪或肝脏中,饱和脂肪酸(SFAs)和单不饱和脂肪酸(MUFAs)含量较高,且与组织脂肪含量密切相关;而多不饱和脂肪酸(PUFAs)、n-3系多不饱和脂肪酸(n-3 PUFAs)和n-6系多不饱和脂肪酸(n-6 PUFAs)含量较低,且与组织脂肪含量关系不大;大黄鱼和银鲳各肌肉组织中的n-3 PUFAs、二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)含量以及n-3/n-6值高于莫桑比克罗非鱼和草鱼,并与组织脂肪含量呈正相关;冬季草鱼腹部肌肉、莫桑比克罗非鱼尾部肌肉以及日本鳗鲡和银鲳的肝脏中的n-3 PUFAs含量较夏季高。研究表明,脂肪酸组成与物种、食性、水域环境以及季节温度和组织部位均有关系。从补充n-3 PUFAs摄入的角度分析,日本鳗鲡、大黄鱼和银鲳营养价值高于莫桑比克罗非鱼和草鱼,冬季鱼类的营养价值高于夏季。     

Salmonid gill bacteria and their relationship to amoebic gill disease

16S ribosomal RNA gene analysis was used to assess the bacterial community associated with Atlantic salmon, Salmo salar L., gills which were either affected by amoebic gill disease (AGD) or were AGD-negative, in order to determine the role that bacteria may play in the development of AGD. AGD-positive specimens were either infected in the laboratory with Neoparamoeba pemaquidensis, the causative agent of AGD, or were obtained from commercial salmon cages. Samples from laboratory fish maintained in sea water possessed a marine-type community while field samples which had been treated by a series of freshwater baths possessed a more diverse community which included variable proportions of different bacterial ecotypes, including groups typically associated with soil, skin surfaces and faeces. Samples from fish infected with AGD in the laboratory and a sample from one of two salmon cage fish specimens were dominated by a phylotype belonging to the strictly marine bacterial genus Psychroserpens (family Flavobacteriaceae, phylum Bacteroidetes). The phylotype was not detected in any of the AGD-negative samples or in one of two AGD-positive samples obtained from fish subjected to temporary freshwater immersion. The possibility of certain Psychroserpens species as potential opportunistic pathogens associated with salmonid AGD is proposed.     

Comparative genomic insights into the taxonomy of Edwardsiella tarda isolated from different hosts: Marine,freshwater and migratory fish

Edwardsiella tarda, a Gram‐negative member of the family Enterobacteriaceae, has been isolated from many animal species worldwide, especially fish species. Its broad host range indicates the diversity in taxonomy, which attracted the attention of many researchers. Here, we added genome of E. tarda strain isolated from freshwater fish to comparative genomics study for the first time. We sequenced and assembled the genome of E. tarda ASE201307 which was isolated from freshwater Asian swamp eel. ASE201307 genome contained a single circular chromosome of 3.68M with G+C 57.09% content. Comparative genomics including SNP calling, synteny block, Core/Pan genes analysis and phylogeny analysis was conducted among ASE201307 and other Edwardsiella strains isolated from different fish species. Results of SNP analysis and synteny block demonstrated the close relative of ASE201307, FL95.01 and DT which were all isolated from freshwater fish. In further analysis heat map of dispensable genes and phylogenetic tree, all E. tarda strains were divided into two groups. One was isolated from freshwater fish and the other was isolated from marine/migratory fish. Based on all studies above, we proposed the living environment of hosts as a new taxonomic character and divided E. tarda isolated from diseased fish into freshwater group and marine/migratory group.     

Viral haemorrhagic septicaemia virus in marine fish and its implications for fish farming--a review

Viral haemorrhagic septicaemia virus (VHSV) has, in recent decades, been isolated from an increasing number of free-living marine fish species. So far, it has been isolated from at least 48 fish species from the northern hemisphere, including North America, Asia and Europe, and fifteen different species including herring, sprat, cod, Norway pout and flatfish from northern European waters. The high number of VHSV isolations from the Baltic Sea, Kattegat, Skagerrak, the North Sea and waters around Scotland indicate that the virus is endemic in these waters. The VHSV isolates originating from wild marine fish show no to low pathogenicity to rainbow trout and Atlantic salmon, although several are pathogenic for turbot. Marine VHSV isolates are so far serologically indistinguishable from freshwater isolates. Genotyping based on VHSV G- and N-genes reveals four groups indicating the geographical origin of the isolates, with one group representing traditional European freshwater isolates and isolates of north European marine origin, a second group of marine isolates from the Baltic Sea, a third group of isolates from the North Sea, and a group representing North American isolates. Examples of possible transfer of virus from free-living marine fish to farmed fish are discussed, as are measures to prevent introduction of VHSV from the marine environment to aquaculture.     

7种海洋鱼类的生物能量学模式

根据室内流水实验法，定量研究了黄、渤海生态系统7种鱼类能量收支组分，并建立了相应的生物能量学模式。7种海洋鱼类的生物能量学模式豆著不同，并可分为3类：(1)较低代谢和较高生长，如黑鲳、矛尾鳃虎鱼；(2)较高代谢和较低生长，如欧氏六线鱼和黑鲷；(3)代谢和生长均处于中等水平，如真鲷、红鳍东方纯和鲐。其差异原因可能与这7种海洋鱼类的生态习性不同相关。与淡水肉食性鱼类比较，7种海洋鱼类的代谢能明显偏高，表明海洋鱼类属于高代谢消耗、低生长效率型鱼类。     

长江上游铜鱼体内全氟辛烷磺酸(PFOS)残留分布特征

为阐明长江上游鱼类全氟辛烷磺酸(PFOS)的残留分布,本研究于2013年分3次在长江上游不同江段,采集该地主要经济鱼类铜鱼(Coreius heterokon)。采用超高效液相色谱–质谱联用法分析铜鱼肌肉、肝和性腺3种不同组织全氟辛烷磺酸(PFOS)含量。结果表明,铜鱼组织内PFOS检出率为100%,总体均值为2.72 ng/g(0.33~10.14 ng/g)。PFOS含量水平在肝最高(5.56 ng/g),肌肉次之(1.39 ng/g),性腺最低(0.62 ng/g)。不同组织间差异极显著(K-W test,P0.01),表明鱼类肝比肌肉和性腺更易于积累PFOS。在不同采集江段,PFOS含量仅在肌肉组织差异显著(ANOVA,P0.05);在不同年龄组,PFOS含量有随鱼类年龄增长而增高的趋势,且在各组织中差异显著(ANOVA,P≤0.05),该结果表明PFOS含量可能与鱼类摄食内容及生理参数不同有关。与已有研究相比,长江上游铜鱼PFOS暴露水平低于国内外淡水、海水鱼类,目前仍处于一个较低水平。     

Cryopreservation of sperm in marine fish

Since the first work of Blaxter in 1953, fish sperm cryopreservation has been attempted on about 30 marine species. The present paper reviews the techniques used and the results published in these species. Particular attention is paid to the handling procedure of sperm before freezing, the problems of semen ageing and semen contamination with urine. The quality of frozen–thawed semen was evaluated using previously standardized biotests, such as a two‐step motility activation technique adapted for the different species and fertilization assays using a discriminating insemination technique. Most extenders used in marine fish are saline or sugar solutions. From the investigated cryoprotectants, dimethyl sulphoxide (DMSO) generally leads to the best results. Cooling rates range from 8 °C to 99 °C min^?1; the thawing rate is generally high. Compared with freshwater species, a high percentage of spermatozoa survives cryopreservation. Therefore, and because of the simplicity of the techniques, the cryopreservation of marine fish sperm is suited for application in aquaculture.     

Possible applications of modern fish larviculture technology to ornamental fish production

There has been rapid development in the marine foodfishlarviculture technology in Europe since the early eighties,especially in the flat fish, turbot and halibut, and the bass andbream species. The most significant improvements in the eightieswere the introduction of light control, artificial reproductiontechniques, appropriate water treatment and the use of rotifersand Artemia nauplii of specific sizes and in the late eightiesand early nineties the quality enhancement of live food organismsusing specific enrichment techniques. Present research is focusedon the implementation of several microbial techniques to improvethe hygiene of live prey and fish.Many of the modern larviculture techniques being used in marine foodfish could be adapted for application in the ornamental fish industry. For examples, research in the Onamental Fish Section, Primary Production Department, Singapore has demonstrated that the use of freshwater rotifers and Artemia nauplii would enable artificial rearing of Discus in the absence of the parent fish and improve the larval performance of Gouramis and Tetra larvae. The use of such small live food organisms is likely to facilitate breeding of new fish species with small larvae. Research has also indicated that the use of diets containing vitamin C and certain immuno-stimulants improved the stress resistance of guppy. Such techniques would have important application in the fish transport, an important aspect in the ornamental fish industry     

The U.S. Wholesale Market for Marine Ornamentals

The market for marine ornamentals encompasses all live marine species (fish and invertebrates) destined for the aquarium trade. In 1998, U.S. imports and exports were valued at approximately US $1.5 billion at the border (all dollar values cited in this paper are $US). In Florida, cultured freshwater and collected saltwater species accounted for $70 million and $4 million, respectively, in annual dockside revenue. To help explain Florida's marine landings and provide suggestions for future resource management and market campaigns that reflect the perceptions of the industry, a survey of wholesalers was initiated in 1999. Preliminary results indicate that there are several intermediate wholesale markets. Florida firms are closer to the supply as many also collect. Wholesalers in other states handle more freshwater product, are larger, and tend to import a larger share of their inventory. Consolidation is expected to continue, but niche markets for eco-friendly firms are expected to grow. In Florida, marketing strategies should focus on the observed higher survival rates and increasing supply of the popular invertebrate species. Many wholesalers are concerned about additional regulations that could reduce the number of collectors and thereby increase supply variability, a noted weakness of the Florida industry.