The Syndrome of Sea Cucumber （Apostichopusjaponicus） Infected by Virus and Bacteria

A outbreak of disease with symptoms of evisceration and skin ulteration led to mass mortality in sea cucumber Apostichopus japonicus cultivated in indoor ponds near the Dalian coast from December 2004 to April 2005. Spherical virus particles with a diameter of 75-200 nm were found in the cytoplasm of cells in the water-system, the alimentary canal and in the respiratory trees of the diseased and dying sea cucumber individuals by electron microscopic observation of ultrathin sections. Examination by negative stained samples revealed that all the diseased sea cucumbers were infected by the virus, while the healthly ones cultivated outside the contagious area were not. Two bacterial strains were also isolated from the diseased animals. When exposed to a medium containing the virus particles, regardless of whether the bacterial suspension was added, healthy sea cucumbers exhibited identical disease symptoms as the ones in the indoor ponds, and had a mortality of 90%-100%. However, when exposed to a medium in which there was only one of the two bacterial strains, 30%-80% of the sea cucumbers were infected and nearly 20% died. Negative staining showed that the viral particles were detected only in the bodies of the tested animals that were exposed to the viral medium Histopathologically, the diseased sea cucumbers are characterized by karyopycnosis, and disintegration of the endoplasmic reticula and mitochondria in the epithelial cells in the water-system, the respiratory tree and the alimentary canal.     

The Syndrome of Sea Cucumber (Apostichopus japonicus) Infected by Virus and Bacteria

A outbreak of disease with symptoms of evisceration and skin ulteration led to mass mortality in sea cucumber Apostichopus japonicus cultivated in indoor ponds near the Dalian coast from December 2004 to April 2005. Spherical virus particles with a diameter of 75-200 nm were found in the cytoplasm of cells in the water-system, the alimentary canal and in the respiratory trees of the diseased and dying sea cucumber individuals by electron microscopic observation of ultrathin sections. Examination by negative stained samples revealed that all the diseased sea cucumbers were infected by the virus, while the healthly ones cultivated outside the contagious area were not. Two bacterial strains were also isolated from the diseased animals. When exposed to a medium containing the virus particles, regardless of whether the bacterial suspension was added,healthy sea cucumbers exhibited identical disease symptoms as the ones in the indoor ponds, and had a mortality of 90%-100%. However, when exposed to a medium in which there was only one of the two bacterial strains, 30%-80% of the sea cucumbers were infected and nearly 20% died. Negative staining showed that the viral particles were detected only in the bodies of the tested animals that were exposed to the viral medium. Histopathologically, the diseased sea cucumbers are characterized by karyopycnosis, and disintegration of the endoplasmic reticula and mitochondria in the epithelial cells in the water-system, the respiratory tree and the alimentary canal.     

饲料中添加甘草酸对刺参生长、免疫及抗病力的影响

以初始体重为(6.80±0.00)g左右的刺参(Apostichopus japonicus Selenka)为研究对象,在室内循环水系统中进行8周饲喂实验,研究饲料中添加不同梯度的甘草酸对刺参生长、免疫及其抗病力的影响。以基础饲料为对照组,在基础饲料中分别添加50、100和200mg/kg的甘草酸,共配制4种实验饲料。结果表明:饲料中添加甘草酸对刺参的成活率没有影响,各处理组均为100%。饲料中添加200mg/kg甘草酸可显著提高刺参的特定生长率(SGR)(P0.05)。养殖实验结束后,通过注射刺参腐皮综合症致病菌灿烂弧菌(Vibriosplendidus)进行刺参攻毒实验,攻毒后14d内对照组与50mg/kg添加组的累计发病率(分别为38.3%和36.7%)显著高于100和200mg/kg添加组(分别为30.0%和26.7%)(P<0.05)。实验可得到以下结论:(1)饲料中添加200mg/kg甘草酸可以提高刺参养殖的产量,同时可以提高刺参的非特异性免疫力和抗病力;(2)在研究中,全周期养殖期间投喂甘草酸不会产生免疫疲劳或其他副作用。       

Isolation and characterization of a sea cucumber fucoidan‐utilizing marine bacterium

Aims: To isolate a fucoidan‐utilizing strain from seawater for sea cucumber fucoidan degradation. Methods and Results: The utilization of sea cucumber fucoidan was monitored by H₂SO₄–phenol assay for neutral sugar. The bacterium CZ1127 was isolated from seawater and shown to have a relatively large maximum fucoidan‐utilizing rate of 81·5%. CZ1127 was confirmed to belong to the family Flavobacteriaceae by 16S rDNA and physiological analyses. This strain has an ability to utilize fucoidans extracted from various sea cucumbers to different degrees. Both extracellular and intracellular enzymes of CZ1127 could degrade sea cucumber fucoidan, as confirmed by high‐performance size exclusion chromatography. The M_r of sea cucumber fucoidan could be reduced from 792·6 kDa to at least 3·7 kDa by the crude intracellular enzyme of this strain. Conclusions: The marine bacterial strain CZ1127, which belongs to the family Flavobacteriaceae, was found to utilize various sea cucumber fucoidans and furthermore showed promise in sea cucumber fucoidan enzymatic degradation and oligosaccharide preparation. Significance and Impact of the Study: The finding of a novel source can be applied in sea cucumber fucoidan enzymatic degradation. Furthermore, it is the first definite report of a bacterial strain that can utilize the fucoidans from various sea cucumbers.     

Acute peristome edema disease in juvenile and adult sea cucumbers Apostichopus japonicus (Selenka) reared in North China

Acute peristome edema disease (APED) is a new disease that broke out in cultured sea cucumber along the Shangdong and Liaoning province coasts in China, PR, and has caused a great deal of death in Apostichopus japonicus (Selenka) since 2004. Here we report virus-like particles found in intestine epithelium of sea cucumbers reared in North China. It is the first time that sea cucumbers are reported to be infected by virus. Histological examinations showed that the viral inclusion bodies existed in intestine epithelium cells. Electron microscopic examinations show that the virions were spherical, 80-100nm in diameter, and composed of a helical nucleocapsid within an envelope with surface projections. Detailed studies on the morphogenesis of these viruses found many characteristics previously described for coronaviruses. Virus particles always congregated, and formed a virus vesicle with an encircling membrane. The most obvious cellular pathologic feature is large granular areas of cytoplasm, relatively devoid of organelles. Tubular structures within virus-containing vesicles, nucleocapsid inclusions, and double-membrane vesicles are also found in the cytopathic cells. No rickettsia, chlamydia, bacteria, or other parasitic organisms were found.     

Phenotypic and genetic characterization of bacteria isolated from diseased cultured sea cucumber Apostichopus japonicus in northeastern China

During the winter-spring from 2004 to 2006 in northeastern China cultured Japanese sea cucumber Apostichopus japonicus suffered from a serious disease. Clinical signs included swollen mouth, skin ulceration and massive mortality. Clinical samples taken during this period were studied. Thirty-one bacterial samples were isolated from diseased sea cucumbers and identified through biochemical tests, 16S rRNA gene sequence analysis and PCR amplification, followed by pathogenicity determination. The results showed that the 31 isolates belonged to the genera Vibrio (64.5%), Shewanella (12.9%), Serratia (12.9%), Pseudoalteromonas (6.4%) and Flavobacterium (3.2 %). The 3 prominent strains were Vibrio splendidus (41.9%), Shewanella (12.9%) and Serratia odorifera biogroup I (12.9%). Pathogenicity tests demonstrated that 13 out of 31 isolates were pathogenic, including 8 strains of V splendidus, 3 strains of Shewanella sp. and 2 strains of Pseudoalteromonas tetraodonis. The pathogenic V splendidus showed the highest frequency of appearance. Median lethal dose (LD50) values (14 d) of V splendidus, Shewanella sp. and P. tetraodonis were 1.74 x 10(7), 7.76 x 10(6), 7.24 x 10(7) CFU g(-1) body weight of sea cucumber, respectively. The virulences differed by species: Shewanella sp. > V splendidus> P. tetraodonis. This is the first report of Shewanella sp. virulence in sea cucumber.     

刺参海带饲料原料褐藻胶降解菌的分离与鉴定

从海带及刺参养殖环境中筛选有效降解褐藻胶,且对刺参无致病性的微生物,对海带饲料原料进行降解处理,以降低海带饲料中刺参难以消化的褐藻胶成分,显著提高饲料利用率,增加海带原料价值。以褐藻胶为唯一碳源选择培养基初筛;DNS法测定褐藻胶裂解酶酶活;16S r DNA测序及生理生化试验对菌种进行鉴定;高浓度腹腔攻毒试验考察筛选所得菌株对刺参的潜在致病性;分子排阻色谱及高效凝胶色谱法对微生物酶解褐藻胶的终产物进行分析。系统发育树分析表明,菌株WB1与Bacillus amyloliquifaciens有最高同源性,对刺参无潜在致病性;其褐藻胶裂解酶酶解褐藻胶的终产物主要为二糖和三糖,相对含量分别为74.1%和25.9%,平均分子量为516 Da。解淀粉芽胞杆菌WB1可作为一种安全的有益微生物用于刺参海带饲料原料中褐藻胶成分的降解。     

Carriage of potentially fish-pathogenic bacteria in Sparus aurata cultured in Mediterranean fish farms

A bacteriological survey of gilthead sea bream Sparus aurata from different fish farms and culture systems on the Spanish Mediterranean coast was conducted. Three different studies were performed. Study A included hatchery-reared larvae; Study B, periodic examination of randomly sampled growing fish; and Study C, growing fish sampled only during mortality/morbidity events. In Studies B and C, sea cages, earth ponds and indoor tanks were surveyed, and in both cases diseased (showing clinical signs) and non-diseased fish were included. In Study A, a shift from Vibrio spp. (30 d after hatching) to oxidative species (60 d after hatching) was detected, and no mortality events were registered. The percentage of fish yielding bacterial growth were similar in Studies B and C, reaching 57.4 and 61.3%, respectively. A statistically significant relationship between the bacterial carriage and the type of facility was only found in Study B, showing that fish from sea cages had a higher bacterial occurrence than fish from other facilities. A statistically significant relationship between bacterial carriage and signs of disease was found, although the pattern differed in each study. Thus, in Study B only 36.2% of fish yielding abundant bacterial growth were diseased, versus 68.0% in Study C. In total, 25.0% of the fish examined were diseased. Bacterial species composition was similar in asymptomatic and diseased fish, except for a group of V. ichthyoenteri-like isolates that occurred almost exclusively in asymptomatic fish. Dominant bacterial species were V. harveyi and V. splendidus, followed by V. ichthyoenteri-like isolates, Photobacterium damselae ssp. damselae and V. fisheri. Non-fermenters were less frequent but, among them, unidentified halophilic Cytophaga-Flavobacterium isolates and Pseudoalteromonas haloplanktis were the most abundant. An association of individual species with disease was not clear, which suggests the involvement of mixed infections.     

海参资源及其生物活性物质的研究

海参属棘皮动物门海参纲,是海洋中重要的食物和药物资源。全世界海参资源比较丰富,目前已知约有1000种,我国约有140多种。海参含有多种生物活性物质,如多糖、甾醇、皂苷、脂肪酸和毒素等,具有增加免疫力、抗肿瘤、抗凝血、保护神经组织、镇痛、抗真菌、降低血黏度等作用。本综述了国内外海参资源分布、海参生物活性物质组成及其药理作用。     

Evolution of gp85 gene of subgroup J avian leukosis virus under the selective pressure of antibodies

Subgroup J Avian leucosis virus (ALV-J) strain NX0101 was inoculated into chicken embryo fibroblasts (CEF) monolayers in 6-well plates. The six wells of CEF inoculated with NX0101 were divided into groups A (without anti-ALV-J serum in the medium) and B (with anti-ALV-J serum in the medium), then viruses from each well of both groups were separately passed in CEF every 6 d and formed their independent passage lineages. For each lineage of both groups, gp85 genes of the viruses in the 10th, 20th and 30th passages were amplified, cloned and sequenced. The sequence data indicated that the homologies of gp85 at aa level between the primary virus and the passed viruses of different passages of 3 lineages in group A were 97.7%–99.7%; and the homologies of gp85 between the primary virus and the passed viruses of different passages of 3 lineages in group B were 93.8%–96.1%. Analysis of the ratios of nonsynonium (NS) vs synonium (S) mutations of nucleic acids demonstrated that NS/S in 3 highly variable (hr-) regions at aa#110–120, aa#141–151 and aa#189–194 of gp85 in 3 lineages of group A were 2 (8/4), 1(3/3) and 1.3 (4/3), however, NS/S in the same 3 hr-regions of group B were 4.1 (13/3), 4.7 (14/3) and 3.3 (11/3). This study is the first demonstration of influence of immune selective pressure on evolution of ALV-J gp85 by specific antibodies under the controlled in vitro experiments.     

热带珊瑚礁区海参的生境选择与生态作用

珊瑚礁生态系统是一个高生产力、高生物多样性的特殊海洋生态系统,具有为生物提供栖息地、参与生物地球化学循环、防浪护岸、指示水体污染程度等生态功能。珊瑚礁生态系统的突出特点是其生境异质性很高,各种各样的生境斑块为种类繁多、习性各异的游泳和底栖生物提供栖息场所,这些礁栖生物通过参与各项生态过程而形成各种特定的功能群,共同完成重要的生态功能。在热带珊瑚礁生态系统中,海参是大型底栖动物区系的重要一员。种类繁多的海参具有各自不同的生境选择特征,通过摄食、运动等行为活动发挥着改良底质、促进有机物矿化和营养盐再生等生态作用。近几年来,全球热带海参受人类过度捕捞和珊瑚礁退化的影响而面临资源衰退、物种多样性丧失等问题,深入认识其生态学功能、加强热带海参资源保护迫在眉睫。综述了国内外热带珊瑚礁海参的基础生态学研究进展：海参对珊瑚礁生境斑块呈现显著的偏好选择特征以及种间差异和季节变动,不同生境斑块的食物质量、底质类型和水动力条件是影响海参生境偏好的重要因素;海参通过生物扰动可以改变珊瑚礁生境沉积物的含水量、渗透性、颗粒组成、再矿化率、无机营养物质释放速率以及孔隙水的化学梯度,并增加沉积物中的溶氧浓度、促进溶解...     

Entrance and Growth of Lactic Acid Bacteria in Gas-Exchanged, Brined Cucumbers

Entrance of lactic acid bacteria into the interior of brined cucumbers was found to be greatly influenced by gas composition of the cucumbers before brining. Exchange of the internal gas of fresh cucumbers with O₂ resulted in absorption of bacteria into the subsequently brined fruit within a few hours. Bacteria were absorbed into nonexchanged cucumbers to a lesser extent. Little bacterial absorption occurred in N₂-exchanged cucumbers. Stomata of the cucumber skin appeared to be a likely port for bacterial entry. When Pediococcus cerevisiae or Lactobacillus plantarum cells were added to the brine of O₂-exchanged cucumbers, the respective cell types colonized in large numbers within intercellular spaces and vascular elements of mesocarp tissue during fermentation of the cucumbers. Implications of these observations, particularly with regard to bloater formation in brined cucumbers, are discussed.     

Commercial rearing of the sea cucumber <Emphasis Type="Italic">Apostichopus japonicus</Emphasis> in Peter the great bay: Methodical peculiarities and results of the work of a mariculture farm in Sukhodol Bight

Methodical approaches to commercial rearing of sea cucumber at mariculture farms in Peter the Great Bay in the Sea of Japan are discussed. This includes two basic phases, viz., intermediate rearing of underyearlings in cages and sea ranching. The survival rate of juvenile sea cucumbers during intermediate rearing in cages in Sukhodol Bight (Ussuri Bay) was shown to depend on the body size and rearing density of the juveniles and its value varied from 35 to 82%. The survival rate of two-year-old juveniles on artificial reefs reached 85%. Monitoring studies of the bottom sites showed that for the entire period of functioning of the farm, 8 years, a sea cucumber colony with the average distribution density of 1.5 inds/m² was formed on an area of about 30 ha. The harvest of the commercial production of sea cucumbers purchased at hatcheries can be calculated taking the survival rates of juveniles during the first years of their life into account. The calculation of the production of juvenile sea cucumbers picked by collectors was based on an appraisal of the current state of their aggregation (abundance, biomass, and size structure) with use of conservation protection measures (the allowable harvest rate of 6.4%).     

不同水深条件下刺参养殖池塘大型底栖动物群落结构季节性变化特征

于2012年7月至2013年4月调查了荣成靖海湾3个不同水深的刺参(Apostichopus japonicus)养殖池塘内大型底栖动物的构成,以了解不同水深对刺参养殖池塘环境条件的影响以及由此引起的大型底栖生物群落结构的改变。结果表明:3个不同水深梯度池塘(1#浅水位、2#正常水位和3#高水位)底部光照强度、叶绿素a(Chla)和总有机物(TOM)含量存在显著差异,各池塘水温差异不显著。光强、Chla和TOM含量在夏季、冬季和春季均表现为1#池塘显著高于3#池塘;秋季各池塘间光强和TOM含量差异不显著,Chla含量则表现为3#池塘显著高于1#池塘。各季节3个池塘间大型底栖动物在种类组成、丰度、生物量和多样性指数上均存在显著性差异。大型底栖动物丰度和生物量夏季均表现为1#池塘显著高于3#池塘,秋季和冬季则相反;春季1#池塘丰度显著高于3#池塘,生物量则差异不显著。这些差异主要与其各自优势种及其优势度指数大小有关。大型底栖动物多样性指数夏季和秋季均表现为1#池塘高于3#池塘,春季则相反,冬季各池塘间多样性指数差异不显著。单因子相似性分析(ANOSIM)表明,各季节3个池塘间大型底栖动物群落结构均存在显著差异,表明水深梯度对刺参养殖池塘大型底栖动物群落结构造成显著性影响。相似性百分比分析(SIMPER)显示,各季节对3个池塘间大型底栖动物群落差异起主要作用的物种为各个池塘的优势种。典范对应分析(CCA)表明,水深、Chla和TOM含量为影响大型底栖动物群落的主要环境因子。     

Novel lncRNA lncRNA001074 participates in the low salinity–induced response in the sea cucumber Apostichopus japonicus by targeting the let-7/NKAα axis

Salinity fluctuations have severe impacts on sea cucumbers and therefore important consequences in sea cucumber farming. The responses of sea cucumbers to salinity changes are reflected in the expression profiles of multiple genes and non-coding RNAs (ncRNAs). The microRNA (let-7) which is a developmental regulator, the ion transporter gene sodium potassium ATPase gene (NKAα), and the long ncRNA lncRNA001074 were previously shown to be involved in responses to salinity changes in various marine species. To better understand the relationship between ncRNAs and target genes, the let-7/NKAα/lncRNA001074 predicted interaction was investigated in this study using luciferase reporter assays and gene knockdowns in the sea cucumber Apostichopus japonicus. The results showed that NKAα was the target gene of let-7 and NKAα expression levels were inversely correlated with let-7 expression based on the luciferase reporter assays and western blots. The let-7 abundance was negatively regulated by lncRNA001074 and NKAα both in vitro and in vivo. Knockdown of lncRNA001074 led to let-7 overexpression. These results demonstrated that lncRNA001074 binds to the 3′-UTR binding site of let-7 in a regulatory manner. Furthermore, the expression profiles of let-7, NKAα, and lncRNA001074 were analyzed in sea cucumbers after the knockdown of each of these genes. The results found that lncRNA001074 competitively bound let-7 to suppress NKAα expression under low salinity conditions. The downregulation of let-7, in conjunction with the upregulation of lncRNA001074 and NKAα, may be essential for the response to low salinity change in sea cucumbers. Therefore, the dynamic balance of the lncRNA001074, NKAα, and let-7 network might be a potential response mechanism to salinity change in sea cucumbers.     

The alimentary canal of <Emphasis Type="Italic">Blomia tropicalis</Emphasis> (Acari: Astigmata: Echymopodidae): the application of three-dimensional reconstruction technology

The domestic mite species Blomia tropicalis is an important indoor allergen source related to asthma and other allergic diseases in tropical and subtropical regions. Here, we describe the alimentary canal of B. tropicalis with the particular application of three-dimensional reconstruction technology. The alimentary canal of B. tropicalis resembles the typical acarid form consisting of the cuticle-lined foregut and hindgut separated by a cuticle-free midgut. The foregut is divided into a muscular pharynx and an esophagus. The midgut is composed of a central ventriculus, two lateral caeca, a globular colon and a postcolon with two tubiform postcolonic diverticula. The most common cells forming the epithelium of ventriculus and caeca are squamous and cuboidal. The globular cells contain a big central vacuole in the posterior region of the caeca. The epithelium of the colon and postcolon has significantly longer microvilli. The anal atrium is a simple tube with flattened epithelial cells. The spatial measurements of the three-dimensional model suggest that the paired caeca and central ventriculus occupy 55.1 and 34.6%, respectively, of the total volume of the alimentary canal and may play the key role in food digestion. J. Wu and F. Yang contributed equally.     

Molecular characterization of segments S7 to S10 of a southern rice black-streaked dwarf virus isolate from maize in northern China

Southern rice black-streaked dwarf virus (SRBSDV) is a novel Fijivirus prevalent in rice in southern and central China, and northern Vietnam. Its genome has 10 segments of double-stranded RNA named S1 to S10 according to their size. An isolate of SRBSDV, JNi4, was obtained from naturally infected maize plants from Ji’ning, Shandong province, in the 2008 maize season. Segments S7 to S10 of JNi4 share nucleotide identities of 72.6%–73.1%, 72.3%–73%, 73.9%–74.5% and 77.3%–79%, respectively, with corresponding segments of Rice black-streaked dwarf virus isolates, and identities of 99.7%, 99.1%–99.7%, 98.9%–99.5%, and 98.6%–99.2% with those of SRBSDV isolates HN and GD. JNi4 forms a separate branch with GD and HN in the phylogenetic trees constructed with genomic sequences of S7 to S10. These results confirm the proposed taxonomic status of SRBSDV as a distinct species of the genus Fijivirus and indicate that JNi4 is an isolate of SRBSDV. Shandong is so far the northernmost region where SRBSDV is found in China.     

Gut bacterial diversity of farmed sea cucumbers <Emphasis Type="Italic">Apostichopus japonicus</Emphasis> with different growth rates

Farmed sea cucumbers (Apostichopus japonicus) of the same age displayed significantly different body sizes and weights under the same farming conditions. To examine the gut bacterial diversity of sea cucumbers and whether the growth differences between them were related to intestinal microbiota, the bacterial species from intestinal samples of 30 farmed A. japonicus from the same tank (15 large sea cucumbers vs. 15 small sea cucumbers) were characterized based on 16S rRNA gene analysis by means of high throughout sequencing. The results showed that bacterial phylotypes in both sizes of sea cucumbers were closely related to Proteobacteria, Verrucomicrobia, Bacteroidetes, Actinobacteria, Firmicutes, Cyanobacteria, Planctomycete, and Spirochaetes, of which Proteobacteria were predominant (>50%). There were no significant differences in the relative abundances of each bacterial phylotype between the two groups, except for Actinobacteria (P < 0.05). In addition, different species uniquely belonging to all three tested samples in the large group and the small group were found. It was interestingly that Vibrio were absent from both groups. It is likely that the differences in the abundances of Actinobacteria and different species in the two groups may be related to their remarkable disparities in body sizes.     

微生物方法降解刺参养殖池塘中氨态氮的研究进展

随着刺参养殖业的迅速发展,刺参池塘养殖暴露出诸多问题,如水体氨态氮含量高、病害严重、单位产量下降等.传统药物弊端较多,微生物方法成为降解水体中氨态氮含量和预防病害发生的新的有效途径.综合阐述了刺参池塘养殖过程中氨态氮对刺参的危害和微生物降解氨态氮的利弊,并介绍了水体中氨态氮高效降解菌株的筛选以及现有微生态制剂存在的问题,对微生物方法降解刺参养殖池塘氨态氮的前景进行了展望.     

A review of the bacterial flora of teleosts and elasmobranchs, including methods for its analysis

Techniques for the quantitative and qualitative analysis of the commensal bacterial flora of fish are reviewed. The literature concerning the commensal bacterial flora of fish indicates that teleost skin often features 10²–0⁷ organisms per cm² of skin, representing the following taxa, in descending numerical order, Achromobacter, Pseudomonas, Flavo-bacterium and Cytophaga species also coryneform organisms. Actively feeding teleosts appear to have an alimentary canal bacterial flora similar to that of the skin and gills, often there are from 10³–10⁸ organisms per 1.0 g, wet weight, of tissue. According to the limited data available for elasmobranchs Gram–positive bacteria are the predominant component of the bacterial flora on the skin of sharks, though the bacterial flora of North Sea skate ( Raja spp.) is reported as being similar to that of teleosts. The commensal flora of fish, particularly of teleosts, is related to their environment and is influenced by environmental changes that affect the quality of the water. Regular monitoring of the water of commercial fish ponds and aquaria for bacterial quality, temperature, dissolved oxygen concentration and pH, combined with a base–line knowledge of the water's quality, may provide an advanced indication of the presence of bacteria potentially able to produce diseased conditions, and factors that will enhance their growth.