罗非鱼斜管虫病的防治技术

在实际养殖过程中,由于周围环境条件限制和高密度精养,养殖水体水质恶化,鱼体抗病能力下降,容易突发疾病。近年来淡水养殖鱼类特别是罗非鱼,经常出现斜管虫病,该病发展快,一旦发生,如不及时控制,死亡率超过80%以上。一、病原斜管虫病病原体为鲤科斜管虫,属管口目、斜管     

冬季鱼病防治技术要点

冬季是渔业的农闲时节,因为大部分水产养殖的商品鱼类都已捕捞上市,越冬的水产品较少,渔民朋友们很容易放松对水产养殖的日常管理和鱼病防治工作。其实,冬季也是鱼病发病率较高的季节,如果不加强防范,就会给渔业生产造成很大的经济损失,并会影响来年水产养殖的正常进行。因此,冬季防病,十分重要。现将冬季比较常见的鱼病作一介绍,以便指导养殖生产。一、斜管虫病斜管虫病的病原体是鲤斜管虫,大量侵袭鱼类皮肤和鳃时,表皮组织因受刺激而分泌大量粘液,同时组织被破坏,严重影响鱼的呼吸机能,随着大批死亡,在鱼苗、鱼种阶段特别严重。防治方法:(…     

广东1月水产养殖病害预测预报

<正>1月份是广东省最低温季节,寒潮频袭,甚至可能出现较长时间的低温阴雨天气,水霉病、小瓜虫病发生风险很大,发病率大幅上升,在局部地区甚至有流行和暴发的可能,养殖生产者要提前做好预防措施。对不耐寒的温水性鱼、虾类,应采取保温措施,防止冻死、冻伤。养殖品种冻伤后极易感染水霉病、寄生虫病而引起大量死亡,加强越冬管理,避免冻死、冻伤和暴发病害,造成经济损失。一、病情预测淡水养殖鱼类易发生车轮虫病、斜管虫病、小瓜虫病和水霉病等,各淡     

广东12月水产养殖病害预报

一．12月病害发生情况预测 12月份广东省进入冬季,气温、水温逐步下降．昼夜温差较大,预测海、淡水养殖水生动物病害发病牢会有所下降,但养殖鱼类烂鳃病、肠炎病、细菌性败血症、水霉病、指环虫病、车轮虫病、斜管虫病、小瓜虫病、     

广东11月水产养殖病害预报

11月病害发生情况预测 11月份我省气温、水温开始降低,昼夜温差大．预测海、淡水养殖水生动物病害发病率会有所下降。但养殖鱼类出血病、烂鳃病、肠炎病、细菌性败血症、指环虫、车轮虫病、斜管虫病、小瓜虫、对虾白斑病、红腿病和不明病因病等病害的发病率仍处于较高水平,应提前做好防控工作。     

海水养殖鱼类主要纤毛虫病及其防治方法

总结了海水养殖鱼类盾纤毛虫病和隐核虫病的研究进展,对其病原的特性、发病症状、诊断技术和防治方法等进行了详细论述,并对今后的研究重点进行了分析,以期为防治纤毛虫病提供有益参考。     

累枝虫病对鳜鱼苗种的危害与防治

累枝虫病通常对虾、蟹等甲壳类水生动物危害严重,对淡水养殖鱼类危害不大。但是近几年来,在鳜鱼苗种培育过程中,出现了累枝虫病危害苗种正常生长并造成苗种死亡的现象,给养殖业者造成了一定的经济损失。笔者在多年的鳜鱼苗种生产过程中对累枝虫病的危害与防治有一些体会和经验,现总结如     

广东1月水产养殖病害测报

1月份是广东气温、水温较低的季节,预测海、淡水养殖水生动物大部分病害的发生率相对较低,但水霉病、小瓜虫病将大幅上升,甚至可能会在局部地区出现流行和暴发,某些低温期易发的病毒性病也有发生的可能,养殖生产者一定要提前做好预防。鱼类的烂鳃病、细菌性败血症、溃疡病、指环虫、车轮虫、斜管虫,对虾的白斑病、红腿病等病害也仍然有高发的可能,应注意预防。     

鱼类小瓜虫病的防治措施

简述了小瓜虫病对鱼类养殖造成的危害。提出在池塘和网箱养殖模式下小瓜虫病的防治措施。包括清理池塘、定期对网箱消毒、严格执行检疫和隔离程序、杜绝外源性输入和交叉感染、加强鱼类的免疫和抗病能力等,尝试用天然植物提取物防治鱼类小瓜虫病。     

水泥池鱼病防治技术

近年来，工厂化养殖发展迅速。利用水泥池养殖黄鳝、泥鳅、金鱼或进行淡水鱼种的暂养，可获得较好的效益。但由于水泥池水体小，养殖密度大，因此很容易发病。现将暂养在水泥池中的彭泽鲫鱼种暴发斜管虫病的防治实例分析如下，并就水泥池防治鱼病的注意事项进行分析，以期有效地指导生产，减少病害造成的损失。     

Suitability of different salmonid strains as hosts for the endangered freshwater pearl mussel (Margaritifera margaritifera L.)

• 1. The complex life cycle of endangered European freshwater pearl mussel Margaritifera margaritifera L. involves an obligatory parasitic phase on a host fish. Knowledge on the host–parasite interaction and on the suitability of different host fish species and strains is required both for the management of wild fish and mussel populations as well as for improving the efficiency of captive breeding methods.
• 2. In this study, the suitability of different salmonid strains for hosting glochidia was tested, including Danube salmon (Hucho hucho L.) and three brown trout (Salmo trutta L.) strains from inside and outside the freshwater pearl mussel distribution range. All brown trout strains as well as Danube salmon were successfully infected with freshwater pearl mussel glochidia and encystment of mussel larvae was detected.
• 3. One brown trout strain originating from the natural pearl mussel distribution range was identified as the most suitable host, revealing the highest fish‐weight‐normalized infection rates and highest glochidial growth rates, whereas endemic Danube salmon was least suitable. Under natural conditions, the role of Danube salmon may be attributed to the long‐distance dispersal of glochidia in the Danube system, whereas sedentary brown trout appear to be the most important hosts at a local scale.
• 4. Successful infection of suitable hosts and the maintenance of these host–parasite systems in calcareous water were demonstrated in this study. These results indicate that neither the infection process nor the encystment phase of freshwater pearl mussels is dependent on low lime concentrations.
• 5. The results of this study suggest that careful selection and management of appropriate host fish strains is mandatory for sustainable conservation management of freshwater pearl mussel populations. Copyright © 2010 John Wiley & Sons, Ltd.

     

Early‐stage sea lice recruits on Atlantic salmon are freshwater sensitive

Sea lice are significant parasites of marine and brackish farmed fishes. Freshwater bathing is a potential control option against numerous sea lice species, although has been viewed as futile against those that are capable of tolerating freshwater for extended periods. By comparing freshwater survival times across host‐attached stages of Lepeophtheirus salmonis (Krøyer), a key parasite in Atlantic salmon farming, we show the first attached (copepodid) stage undergoes 96–100% mortality after 1 h in freshwater, whereas later attached stages can tolerate up to 8 days. Thus, regular freshwater bathing methods targeting the more susceptible attached copepodid stage may successfully treat against L. salmonis and potentially other sea lice on fish cultured in marine and brackish waters.     

Induced breeding and larval rearing of the endangered Australian freshwater fish trout cod, Maccullochella macquariensis (Cuvier) (Percichthyidae)

Abstract. The endangered Australian freshwater fish trout cod, Maccullochella macquariensis (Cuvier), was the subject of a captive breeding programme to produce fry for reintroduction into the wild. Trout cod broodfish were maintained in earthen ponds for up to 5 years and underwent gonadal maturation each spring but did not spawn in the ponds. Infestations of the protozoan parasite Chilodonella hexasticha caused the death of at least 21 broodfish. Mature fish, removed from ponds when water temperatures had reached or exceeded 16°C, had a higher proportion of atretic oocytes and fewer fish spawned successfully compared to fish removed at lower temperatures. Ovulation was induced by a single injection of 1000–3000 iu/kg HCG. Between 1188 and 11338 eggs ranging from 2·5 to 3·6 mm in diameter were stripped from individual fish. Hatching commenced on days 5–9 and continued for up to 10 days (at 15·5–23°C). Larvae commenced feeding on days 21–25. Trout cod larvae were grown out to fry (363.3–48.6mm total length [TL]) in fertilized fry rearing ponds then released. Between 1986 and 1989, 8420 trout cod fry were released into several sites in the upper Murray River and upper Murrumbidgee River, and reports indicate that released fish are surviving.     

铁岭市主要养殖区鱼病调查与分析

2007年5月至2009年9月,通过对铁岭市辖区的开原市、铁岭县、昌图县淡水鱼类主要养殖区的池塘和小型水库鱼类常见鱼病种类、发病季节、流行情况及危害程度进行调查与分析,初步摸清了近三年鱼病的种类、流行、发病特点.共发现鱼病12种:其中细菌性鱼病6种、寄生虫病5种、真菌类鱼病1种,其中细菌性鱼病和寄生虫性鱼病是主要水产养...     

Effects of experimental infection by Caligus rogercresseyi (Copepoda: Caligidae) on the common jollytail, Galaxias maculatus (Osmeriforme: Galaxiidae) (Jenyns, 1842) in Chile

Galaxias maculatus, the common jollytail, is a native smelt fish with a lacustrine or diadromous life cycle. In Chile, the rearing cycle of this fish includes a freshwater and a marine phase. Several diseases and parasites reported for the freshwater phase could be avoided by rearing the fish in salty or brackish water. Nonetheless, this alternative could result in Caligus rogercresseyi infections. The objective of this study was to evaluate experimentally the capacity of C. rogercresseyi to infect the common jollytail and the effects this parasite may cause to the fish. Prevalence and intensity of experimental C. rogercresseyi infections on G. maculatus were estimated and the effects of this parasitosis on the fish were evaluated on fish survival, weight loss, swimming behavior, and skin damage. Two experiments were carried out with adult fish taken from the Maullín Estuary. Fish were acclimatized to a salinity of 32 ppt and divided into two groups of 20 fish each. The experimental group was infected with copepodid stages of C. rogercresseyi and the other was used as a control. The fish were kept in individual tanks until observing ovigerous female copepods. C. rogercresseyi recognizes G. maculatus as a host under experimental conditions and optimal salinity for the parasite. Results show that under experimental condition copepodid stage can successfully infect the fish, developing to the adult stage, mating, and producing eggs (females). C. rogercresseyi caused alterations in fish behavior, superficial body damage, weight loss, and mortality. Rearing the common jollytail in salty water should take into consideration measures to control these infections as they can damage fish and affect surrounding wild fish populations. There are no records of this parasite in natural common jollytail populations; however, our understanding of the ecological role played by the common jollytail in C. rogercresseyi transmissions among sympatric host species could be greatly improved through further research related to host preferences and epidemiological data for different sympatric host species.     

Transmission Ecology and Larval Behaviour of Camallanus cotti (Nematoda, Camallanidae) Under Aquarium Conditions

The parasitic fish nematode Camallanus cotti has been reported from a number of freshwater fish species around the world. Its wide geographical distribution seems mainly to be the result of anthropogenic dissemination due to extensive ornamental fish trade. In most reports it is assumed that C. cotti's life cycle involves cyclopoid copepods as intermediate host and various freshwater fishes as final host. However, the species' relatively frequent and persistent occurrence in aquaria worldwide strongly indicates flexibility in its life cycle, i.e. the ability to infect the final host directly. The present study has shown that under aquaria conditions, without any presence of copepods, C. cotti is able to infect various phylogenetically distant fish species directly for at least three generations. It was further shown that the infective free-living first-stage larvae may survive for more than three weeks in the host-external environment and that their host-attracting behaviour is not precluding direct transmission to the final fish host. Any treatment for C. cotti under aquaculture or aquarium conditions should be directed towards both individual infected fish hosts as well as the free-living larvae on the substrate. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic relationships among members of the Ichthyobodo necator complex: implications for the management of aquaculture stocks

Abstract Ichthyobodo necator (costia) is a common and important flagellate parasite that infests the skin and gills of many freshwater and marine fish. Costia infestations are often fatal and cause significant aquaculture losses worldwide. Recently it has been demonstrated that Ichthyobodo is a multispecies complex with differing host preferences. Knowing if those species have broad or narrow host specificity has important implications for the management of costia. To address the question of host specificity, genomic DNA was isolated from Ichthyobodo trophonts collected from rainbow trout, Oncorhynchus mykiss, koi, Cyprinus carpio, mirror carp, C. carpio, goldfish, Carassius auratus, channel catfish, Ictalurus punctatus, swordtail, Xiphophorus helleri, and Japanese flounder, Paralichthys olivaceus. The small subunit ribosomal RNA (SSU rRNA) gene from each isolate was analysed with previously published Ichthyobodo sequences using Bayesian phylogenetic methods. The internal transcribed spacers (ITS) from six isolates were also PCR-amplified, cloned and sequenced. Both the SSU rRNA phylogenetic analysis and the ITS rRNA sequence data support grouping the 22 Ichthyobodo isolates examined into a complex of nine different species. Many of these species were frequently isolated from multiple hosts, indicating that exchange of infested fish from one region to another has a high potential for spreading the disease. In one instance, the same species was obtained from marine and freshwater fish, further suggesting that certain Ichthyobodo species may not be limited by salinity.     

额尔齐斯河三代虫种类研究及新纪录种记述

为探究额尔齐斯河水域中鱼类寄生三代虫的种类以及感染情况,给新疆水产业的发展及我国三代虫的研究提供基础资料,2009年8月至2014年8月选取额尔齐斯河的北屯镇、185团场、布尔津和哈巴河4个采样点,自捕或者从当地渔民处购买材料鱼,通过染色观察三代虫的形态特征,对其几丁质结构进行绘图、测量及比较,同时对不同种类三代虫的感染率、感染强度、感染丰度以及宿主专一性进行分析。结果表明,4个采样点共发现三代虫14种,其中丁 三代虫（Gyrodactylus tinca Malmberg,1957）、白斑狗鱼三代虫（Gyrodoctylus lucii Kulakowskaja,1951）、梭鲈三代虫（Gyrodoctylu luciopercae Gusev,1962）、马氏三代虫（Gyrodactylus markakulensis Gvosdev,1950）均是国内首次发现,为新纪录种;感染率最高的为鲤（Cyprinus carpio）（23．94％）,最低的为河鲈（Perca fluviatilis）（0．74％）,除东方欧鳊（Abramis brama orientalis）、散鳞镜鲤（Cyprinus carpio haematopterrus）和鲤外,其余的感染率均不超过10％;银鲫（Carassius auratus gibelio）、散鳞镜鲤和鲤为易感宿主,方均比（S2／X）都大于1,呈聚集分布;其余的小于1,呈均匀分布。三代虫宿主专一性较强,但有少数种类三代虫寄生2～4种宿主的情况,也存在同一宿主感染2～3种三代虫的现象,与单殖吸虫的宿主专一性基本一致。     

Clinical assessment of chloramine-T and freshwater as treatments for the control of gill amoebae in Atlantic salmon, Salmo salar L.

Infections of gill amoebae that manifest as amoebic gill disease (AGD) occur in Atlantic salmon in Tasmania. The treatment of choice is freshwater bathing; however, the effectiveness of this treatment has declined over time. In this experiment, cage trials of chloramine‐T (Cl‐T) to treat AGD in Atlantic salmon were conducted over 3 months, and involved an initial bath in either freshwater or seawater with Cl‐T, followed by a second bath 6 weeks later. Amoeba densities were reduced to 50–80% of original values for both treatments. Neoparamoeba sp. density was not affected by bathing, and was not significantly different over the course of the experiment. Lesion prevalence was higher for Cl‐T‐treated fish than for freshwater‐treated fish, with overall prevalence levels of 14.30±1.00% and 8.03±0.57% respectively. This was also seen for gross gill scores. In the fortnight after each of the two baths, Cl‐T‐treated fish had significantly higher lesion levels, although this difference was then resolved by 4 weeks post bathing. The use of Cl‐T in seawater is at least as effective as freshwater at reducing amoebae density, and may be a more practical alternative when freshwater is in short supply.     

Freshwater mussels increase survival of largemouth bass (Micropterus salmoides) in drying pools

Between global climate change and anthropogenic water needs, freshwater systems are becoming more intermittent, stressing organisms adapted to perennial waters. Drought-induced intermittency concentrates aquatic organisms into drying pools. These pools represent refugia from desiccation but apply other stressors, such as extreme temperatures and increased competition for dwindling resources. In the Southern United States, fishes and freshwater mussels are often concentrated together in drying pools during seasonal, summer droughts. This can result in increased competition for food among invertivorous fish, but also increased food abundance for these fish because mussels increase macroinvertebrate abundance. Further, since mussels require fish as hosts for their ectoparasitic larval phase, glochidia, competition with their host during this biologically active time is detrimental to mussels. We conducted an experiment to examine the effects of freshwater mussels on trophic resources and fish survival in drying pools. We stocked mesocosms with juvenile largemouth bass that were infected or uninfected with glochidia and tracked abiotic conditions, trophic resources and fish survival for 10 days. We found that fish survived longer in the presence of adult mussels, regardless of their infection status. We suspect that prey items supplemented by adult freshwater mussels increased the survival of fish. Thus, the presence of adult mussels and the resources that increase in their presence potentially mitigate stress to fish in “ecological crunch times.” By conserving mussels, fish populations might withstand droughts more easily.