Malachite-green-removing properties of a bacterial strain isolated from fish ponds in Thailand

Malachite green (MG) has been focused on as a biotreatment target and its biological properties have also been an issue in food fish aquaculture. An MG-removing bacterium was isolated from aquaculture fish pond sediment samples in Thailand. The isolate, strain T-5-2, is a Gram-negative, aerobic rod-shaped bacterium, and has been identified as a member of the Pseudomonas putida group. Proton nuclear magnetic resonance spectroscopy (¹H-NMR) analysis of a broth culture medium containing MG showed that the concentration of MG decreased markedly and that other molecules, including leucomalachite green (LMG), were generated. Moreover, liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis showed that the MG concentration in the broth culture medium continuously decreased. This analysis also demonstrated that the concentration of LMG initially increased and then gradually decreased. Furthermore, gas chromatography–mass spectrometry (GC–MS) analysis showed 4-(dimethylamino)benzophenone (4DABP) as a degradation component of MG, which was confirmed by ¹H-NMR and LC–MS/MS analysis. These findings suggest that this bacterial strain can remove MG in broth culture and degrade it to certain metabolites, including LMG and 4DABP. This study is the first detailed evaluation by the combination of LC–MS/MS, GC–MS, and ¹H-NMR analyses of an MG-removing bacterium isolated from Thai aquaculture fish ponds.     

The Potential and Sustainability of Aquaculture in India

ABSTRACT

India is a very populous country with more than one billion people. In order to provide food for this growing population, serious environmental problems may result. Despite many benefits from the green, blue, and silver revolutions adopted in India, there has been much concern resulting from intensive agricultural practices that led to environmental problems in both terrestrial and aquatic ecosystems. Increasing demand for aquatic resources also caused inland fisheries to decrease over the past few decades. The location of aquaculture projects, landscape destruction, soil and water pollution by pond effluents, over-exploitation of important fish stocks, depletion in biodiversity, conflicts over agriculture and aquaculture among various stakeholder groups over resource and space allocation, and international fish trade controversies have threatened the long-term sustainability of fisheries and aquaculture industries. The subject of sustainable aquaculture has not been adequately projected in terms of current aquaculture practices aimed to boost a rural economy. This review briefly describes the key issues of aquaculture unsustainability in terms of intensive aquaculture, nutrient enrichment syndrome, soil and groundwater salinization, destruction of mangroves, loss of biodiversity, marine pollution and loss of fish stock, use of aquachemicals and therapeutics, hormone residues, etc. The strategies for sustainability have been highlighted with respect to rice-cum-fish culture, carp polyculture, integrated farming with livestock, rural aquaculture, intensification of small farms, wastewater-fed aquaculture, crop rotation, probiotics, feed quality, socioeconomic considerations, environmental regulations and fisheries acts, transboundary aquatic ecosystems, impact of alien species, ethical aspects of intensive aquaculture, responsible fisheries, and environmental impact assessment. A suggested model outlines the feedback mechanisms for achieving long-term sustainability through improved farm management practices, integrated farming, use of selective aquachemicals and probiotics, conservation of natural resources, regulatory mechanism, and policy instruments.     

Historical aspects, current status and prospects of pejerrey aquaculture in South America

The pejerrey Odontesthes bonariensis (Valenciennes, 1835) is an inland water fish from the Pampas region comprising part of Argentina, Uruguay and the South of Brazil. Pejerrey is a very popular fish in this region and has a long history of domestic and international introductions, which attests to the high quality and market value of its flesh, as well as its attractiveness as a game fish. The desirable characteristics of pejerrey also make it a good candidate for aquaculture, and the first trials on pejerrey cultivation (atheriniculture) were started more than a century ago in Argentina. In spite of the considerable interest in its development, little progress has been made and atheriniculture is still restricted to propagation and stocking for sport fishing purposes. In this review, we summarize the history of atheriniculture and the biological, technological, scientific, cultural and infrastructural constraints to pejerrey aquaculture development thus far. We also suggest possible scenarios of pejerrey aquaculture development compatible with the socio–economic conditions of South American countries. Our projections also take into consideration recent scientific findings on the biology of pejerrey and technological advances in seafood processing, storage and transportation, as well as the latest trends of seafood consumption and international markets. The best production strategy remains to be determined by trial and error but it is likely that, initially, production should focus on a differentiated, high‐quality fish for the premium or international markets rather than attempting to compete with the cheap fish from natural sources. An international cooperation project with Japan has successfully demonstrated the feasibility of breeding pejerrey in captivity and mass producing seeds efficiently in Argentina, and has provided the foundation for the development of intensive and extensive farming of this species.     

MC与MG对尼罗罗非鱼和大口黑鲈游泳行为的影响

尼罗罗非鱼(Tilapia nilotica)和大口黑鲈(Micropterus salmoide)是中国主要的淡水经济鱼类,其养殖过程中常遇到微囊藻毒素(Microcystin,MC)与孔雀石绿(Malachite green,MG)的危害。MC和MG通过食物链在人体中富集,给人类的健康造成了严重的威胁。研究测定了人工饲养的尼罗罗非鱼和大口黑鲈在含有MC和MG的水体中的行为反应。结果表明,尼罗罗非鱼和大口黑鲈在0.2和0.5μg/L MC-LR的水体中处理60min内,其游泳行为相对于对照组无显著性差异,然而,在0.5mg/L MG的水体中处理30min后,尼罗罗非鱼胸鳍摆动频显著上升,大口黑鲈胸鳍摆动频率也在25、30、45min等3个不连续的时间点出现显著的变化。说明尼罗罗非鱼和大口黑鲈对天然毒素MC具有较强的抵抗能力,而对人工毒素MG较为敏感;胸鳍摆动频率可作为尼罗罗非鱼和大口黑鲈一个较为敏感的反映环境变化的行为指标。     

The development of the Norwegian wrasse fishery and the use of wrasses as cleaner fish in the salmon aquaculture industry

Norway leads the world aquaculture production of Atlantic salmon Salmo salar and farmed Norwegian Atlantic salmon is currently consumed around the globe. However, sea lice infestation is a major problem faced by the salmon aquaculture industry in Norway and elsewhere. The use of wild-caught cleaner fish, mainly wrasses, has been recommended over the other available methods as the most economical and environmentally friendly option to control sea lice infestation in salmon farming. Here, we review the development of the Norwegian wrasse fishery and the use of wrasses as cleaner fish. In this document, we address the sea lice problem and introduce the main wrasse species employed as cleaner fish, document the cleaning behaviour of wrasses, present the development of a new wrasse fishery associated with the salmon aquaculture industry, and finally, we identify the main challenges associated with the intensive use of wild-caught cleaner wrasses and provide some insight for future directions of the wrasse fishery and further development of aquaculture techniques to supply salmon facilities with domesticated cleaner fish.     

Viral infections in cultured fish and shrimps: current status and treatment methods

Aquaculture is growing post-haste in recent years particularly in the fish and shrimp production. The rapid growth of aquaculture and increasing demand for fish have led to a rapid development of the fish and shrimp industry, resulting in increased production of both fish and shrimps. As a result, there is a greater risk of disease outbreaks. Mass mortalities in aquaculture are primarily due to infectious diseases caused by bacteria, viruses, and fungi. Among them, viral diseases are the most devastating, causing huge loss in the production of both cultured fish and shellfishes. There are several effective methods of treatment for these disease outbreaks. This review focuses on various methods of controlling the viral pathogens using various treatment methods like use of medicinal plants and seaweed extracts, bioactive compounds from actinomycetes, vaccines, probiotic microbes, chemicals, nanoparticles, and green synthesis of nanoparticles.

     

Review of the Application of Garlic,Allium sativum,in Aquaculture

The extensive use of antibiotics and various chemical compounds has resulted in drug residue and resistant pathogens in treated fish. Drug residue not only pollutes the environment, but also threatens human consumers. In contrast, garlic as a well‐known natural antibiotic that causes no environmental or physical side effects has shown to be effective for the treatment of many diseases in humans and animals owing to its antimicrobial, antioxidant, and antihypertensive properties. In aquacultural operations, garlic with dose optimization is strongly recommended. This review focuses on the application of garlic in various fish diseases treatments and the prospects of using garlic preparations in aquaculture.     

Current research on the use of plant‐derived products in farmed fish

Over the years, aquaculture has shown increasing development in terms of production. However, due to intensive farming practices, infectious diseases represent the main problem in fish farms, causing heavy economic losses. The use of antibiotics for controlling diseases is widely criticized for its negative impact, including selection of antibiotic‐resistant bacterial strains, immunosuppression, environmental pollution and accumulation of chemical residues in fish tissues. On the other hand, though vaccination is the most effective prophylactic method of preventing disease outbreaks, the development of effective formulations is often hindered by high production costs and the antigenic heterogeneity of the microbial strains. Recently, there has been increased interest in the possibility of using medicinal herbs as immunostimulants, capable of enhancing immune responses and disease resistance of cultured fish. Plant‐derived products seem to represent a promising source of bioactive molecules, being at the same time readily available, inexpensive and biocompatible. The aim of this article is to provide an overview of recent research dealing with the use of medicinal plants in aquaculture. Special attention is given to the information about the effects of plant extracts/products on fish growth, haematological profiles, immune responses and resistance to infectious diseases.     

Probiotics in fish and shellfish culture: immunomodulatory and ecophysiological responses

Aquaculture is emerging as one of the most viable and promising enterprises for keeping pace with the surging need for animal protein, providing nutritional and food security to humans, particularly those residing in regions where livestock is relatively scarce. With every step toward intensification of aquaculture practices, there is an increase in the stress level in the animal as well as the environment. Hence, disease outbreak is being increasingly recognized as one of the most important constraints to aquaculture production in many countries, including India. Conventionally, the disease control in aquaculture has relied on the use of chemical compounds and antibiotics. The development of non-antibiotic and environmentally friendly agents is one of the key factors for health management in aquaculture. Consequently, with the emerging need for environmentally friendly aquaculture, the use of alternatives to antibiotic growth promoters in fish nutrition is now widely accepted. In recent years, probiotics have taken center stage and are being used as an unconventional approach that has numerous beneficial effects in fish and shellfish culture: improved activity of gastrointestinal microbiota and enhanced immune status, disease resistance, survival, feed utilization and growth performance. As natural products, probiotics have much potential to increase the efficiency and sustainability of aquaculture production. Therefore, comprehensive research to fully characterize the intestinal microbiota of prominent fish species, mechanisms of action of probiotics and their effects on the intestinal ecosystem, immunity, fish health and performance is reasonable. This review highlights the classifications and applications of probiotics in aquaculture. The review also summarizes the advancement and research highlights of the probiotic status and mode of action, which are of great significance from an ecofriendly, sustainable, intensive aquaculture point of view.     

LMG在养殖水体中的残留及其在鱼肌肉中的积累

检测曾投放过孔雀石绿(MG)养殖池塘中水样MG和隐性孔雀石绿(LMG)含量,并以此数据为基础通过室内模拟实验研究了不同浓度LMG养殖水体中生长的罗非鱼(Tilapia)和淡水白鲳(Colussoma brachypomum)肌肉中的积累情况。结果显示:所选取的5个池塘中LMG平均含量为30.32 ng/mL,6个月前使用过孔雀石绿的5个鱼塘的养殖水体中仍有一定量LMG残留。室内模拟实验显示:在LMG初始浓度为1.00 ng/mL的养殖水体中,LMG在罗非鱼和淡水白鲳肌肉中积累浓度分别高达60.0 ng/g和70.8 ng/g;罗非鱼肌肉中脂肪含量为0.53%,淡水白鲳为0.75%,说明脂肪含量高的淡水白鲳更容易积累LMG。同时发现,罗非鱼和淡水白鲳积累LMG浓度与水体中LMG浓度成正相关。     

ＭＣ与ＭＧ对尼罗罗非鱼和大口黑鲈游泳行为的影响

尼罗罗非鱼(Tilapia nilotica)和大口黑鲈(Micropterus salmoide)是中国主要的淡水经济鱼类,其养殖过程中常遇到微囊藻毒素(Microcystin,MC)与孔雀石绿(Malachite green,MG)的危害。MC和MG通过食物链在人体中富集,给人类的健康造成了严重的威胁。研究测定了人工饲养的尼罗罗非鱼和大口黑鲈在含有MC和MG的水体中的行为反应。结果表明,尼罗罗非鱼和大口黑鲈在0.2和0.5μg/L MC-LR的水体中处理60min内,其游泳行为相对于对照组无显著性差异,然而,在0.5mg/L MG的水体中处理30min后,尼罗罗非鱼胸鳍摆动频显著上升,大口黑鲈胸鳍摆动频率也在25、30、45min等3个不连续的时间点出现显著的变化。说明尼罗罗非鱼和大口黑鲈对天然毒素MC具有较强的抵抗能力,而对人工毒素MG较为敏感;胸鳍摆动频率可作为尼罗罗非鱼和大口黑鲈一个较为敏感的反映环境变化的行为指标。     

孔雀石绿对日本鳗鲡的背景污染试验

用高压液相色谱法检测孔雀石绿和隐性孔雀石绿,研究了水体使用孔雀石绿后,池塘底泥孔雀石绿残留和泥土背景污染导致的鳗鲡肌肉中孔雀石绿的残留和消除.连续使用三次孔雀石绿24 h后,水体中无孔雀石绿残留.池塘使用孔雀石绿溶液浸泡后,导致池底泥沙中孔雀石绿残留,部分采样点检测到隐性孔雀石绿于泥沙中残留.池底孔雀石绿的残留,将导致鳗鲡孔雀石绿在肌肉中的残留,隐性孔雀石绿将长期于肌肉中滞留.孔雀石绿背景污染的池塘,应改造至无背景污染后使用,才能保障鳗鲡无孔雀石绿残留.     

工厂化循环水养殖系统中流场特性与鱼类互作影响的研究进展与展望

随着人口与经济的发展,水产养殖业在世界范围内迅速兴起,集约型工厂化循环水养殖因其高密度、低污染、高效率等独特的优势,契合水产养殖业绿色发展理念,已成为水产养殖转型升级的重要方向之一。水作为循环水养殖系统中重要的环境因子,其流态能够直接影响鱼类的生长及福利,同样,鱼类存在及运动也会影响到系统流态的构建。本文综合分析了循环水养殖系统中流场条件对不同鱼类生长发育及福利的影响,鱼类及其运动行为对养殖池内水动力条件及性能的影响,以及鱼类对养殖池内流场流态、水体混合等的影响。将研究鱼类运动对流场特性的影响方法主要归纳为实测法和数值研究,通过对比分析2种方法的优点和不足之处,并结合当前循环水养殖产业系统构建中的问题提出针对性方法建议,旨在为系统中水动力条件的设计拓展思路,促进循环水养殖产业流态构建向“鱼”与“水”兼顾的方向发展。     

鳜养殖概况及摄食调控机制研究进展

鳜是我国名贵的淡水经济鱼类,2019年其养殖产量已达33万t。本文从养殖现状、养殖模式及良种选育等方面介绍鳜的养殖概况。同时,鳜摄食习性独特,终生以活鱼为食。养殖生产中,主要以活饵料鱼直接饲喂,这种以鱼养鱼的方式不仅资源利用率低,对环境和资源的破坏也极大。据此,本文从环境因素和饵料性质等方面概述了影响鳜摄食的外在因素,并从摄食感觉器官和摄食调控因子剖析鳜摄食特性的内在因素,这有助于通过人工干预的方式调整鳜的摄食习性,为其转食配合饲料提供必要的支撑。此外,需加强鳜摄食调控机制及营养生理需求特性的研究,实现鳜配合饲料的突破,促进其养殖业的绿色健康发展。     

Controlling of geosmin and 2‐methylisoborneol induced off‐flavours in recirculating aquaculture system farmed fish—A review

Recirculating aquaculture system (RAS) is an increasingly popular alternative to open aquaculture production systems. However, off‐flavours and odours can accumulate in the fish flesh from the circulating water and decrease the fish meat quality. Off‐flavours are typically caused by geosmin (GSM) and 2‐methylisoborneol (MIB) that are lipophilic compounds formed as secondary by‐products of bacterial metabolism. Even though GSM and MIB are not toxic, they often are disliked by consumers, and both have very low human sensory detection limits. Multiple methods have been suggested to remove or decrease GSM and MIB in fish, including ozonation, advanced oxidation processes (AOP)s and adsorption removal from water using activated carbon and/or zeolites. So far, purging with fresh water is the only efficient method available to remove the off‐flavours. There are multiple analytical methods available for the extraction and separation of GSM and MIB from fish flesh and water. This review discusses the current knowledge of GSM and MIB formation, the challenges faced by RAS farms due to these compounds and process solutions available for their removal.     

氟苯尼考用于水产养殖的安全性

氟苯尼考(florfenicol)，又称氟甲砜霉素，是一种新型广谱高效抗菌药物，自20世纪90年代初开始应用于水产养殖。1990年氟苯尼考首次在日本上市用于治疗黄尾蛳(Seriola lalandei)、真鲷(Pagrosomus major)、银大马哈鱼(Oncorhynchus kisutch)、日本竹笑鱼(Trachurus japonicus)、虹鳟(Oncorhynchus mykiss)、香鱼(Plecoglossus altivelis)、罗非鱼和鳗鱼等的假结核性巴氏杆菌病(pasteurellosis)和链球菌病(streptococcosis)，随后，韩国、挪威、智利、加拿大、英国等分别上市用于治疗专门疾病。中国1999年批准氟苯考尼为国家二类新兽药，在水产养殖上可用于治疗鳗鲡爱德华氏病和赤鳍病。本研究从氟苯尼考抗菌活性与药效学、药代动力学、毒理学、以及药物残留、耐药性等方面探讨其用于水产养殖病害防治的安全性，旨为该药在中国水产养殖中的科学合理应用提供理论参考。     

益生菌对幼鱼生长发育的影响及调控机制

近年来,高密度、集约化的水产养殖模式导致养殖鱼类疾病频发,其中幼鱼发病率和死亡率的上升严重影响水产养殖业的健康快速发展。如何保障幼鱼的健康是当前水产养殖业亟需解决的问题。益生菌能够通过多种方式提高幼鱼的抗病力、增强幼鱼对营养素的摄取、促进幼鱼的生长发育。已有大量的研究阐述了益生菌在幼鱼生长发育及免疫调节中的作用,但相关机制还需深入探究。本文综述了近年来益生菌在幼鱼生长发育及抗病方面发挥的有益作用及其可能的机制,讨论了益生菌在幼鱼养殖应用时可能存在的问题以及发展方向,为益生菌在水产动物幼体养殖中的应用提供了理论参考。     

鱼类免疫增强剂的研究现状与进展

现代水产养殖业追求优质高产,但在大规模高密度的养殖生产中,往往会导致鱼体的抗应激能力下降,病害增多,成活率下降,造成重大经济损失。近年来,国内外学者对鱼类免疫机制及其病害防治方法已进行了大量研究,其中免疫增强剂因能增强机体抗疾病感染的能力,其免疫增强作用所需时间较短,且没有记忆成分,被认为是一种提高鱼体免疫活性及疾病抵抗力的有效方法,具有重要的应用价值。     

Piscine cytochromes P450 (CYP) and their response to antimicrobial drugs

Most research on the P450 (CYP) system in teleosts has been done on environmental factors that influence their induction. Less is known about CYP metabolism of aquaculture antibiotics. This article outlines the impact of aquaculture antimicrobials on the piscine CYP system, with particular regard to interactions with tetracyclines, fluoroquinolones, sulphonamides, berberine and chloramphenicol, as paradigms for current, potential and discontinued piscine antimicrobial drugs. It gives an overview of literature reports and advances in the field of biological significance of the CYP in fish. Emphasis has been placed on highlighting the most significant isoforms for biotransformation of drugs, and their drug response mechanisms. The challenge is to elucidate the differences in responses of CYP enzymes in different species to antimicrobial treatment as they may have relevance for the use of antimicrobials in aquaculture, especially as drug interactions with the fish CYP may alter their distribution, metabolism and elimination. They can impact the metabolism of other drugs metabolized by the same system with an effect on the physiology of fish administered these antimicrobials. Also, they can affect the persistence of residues and the length of the withdrawal period. For food animals such as farmed fish, this knowledge is a fundamental biomedical goal.     

Evaluation of antimicrobial products used in tilapia (Oreochromis spp.) and whiteleg shrimp (Litopenaeus vannamei) aquaculture

Despite the importance of aquaculture increases for feeding the growing world population, professional farm management and proper use of aquaculture products or drugs are needed. It is important to know the quality of commercial antimicrobial products on the market while there is wide use of antimicrobials to treat fish diseases. The most commonly used antimicrobial products were identified from a previous survey, included amoxicillin, enrofloxacin, florfenicol, sulphadiazine, sulphamonomethoxine and sulphadimidine. Eight local chemical supply shops were randomly sampled in representative aquaculture areas in Maoming and Zhanjiang districts of south China in 2013. In this study, only eight products contained active substances within ±10% of the concentration declared on the product label among the 30 different most used commercial products; while six products did not contain any of the declared antimicrobials. Three products without labels were sold as ‘pure antimicrobial’ and had high concentrations of active antimicrobials. Furthermore, most products only provided ambiguous information on the packages on both antimicrobial usage and dosage; and only one product stated how to prepare medicated feed which is important for efficient usage. The results of this study showed that the aquaculture antimicrobial products sold on the market were of low quality and thus compromised effective fish disease treatment. Moreover, insufficient information on products’ labels would provide limited instruction on correct antimicrobial usage. Inspection and supervision by both private companies and the government's sector require strengthening.