三角鲤人工养殖试验

平均体重 150g的三角鲤苗种 11250尾, 采用二级养殖技术养殖 20个月, 成活率 90 .1%, 平均体重 726. 6g/尾, 收获三角鲤 7362. 5kg, 亩产 589kg, 总产值为 515375元, 获利 356458 2元, 平均 28516. 7元 /亩, 饵料系数为 3 .2, 饵料成本占生产成本 48 .2%, 投入产出比为 1∶3. 24。     

龙胆石斑鱼集约化养殖试验

从2002年12月19日引进3~5cm的龙胆石斑鱼苗820尾,经过11个月养殖试验测定,共 存活483条,成活率58.9％,平均体重473g／尾,最大体重950g／尾,养殖期间,饵料系数1.44,饵料效率 69％,养殖总积温7900℃。     

山涧水流水养殖黑脊倒剌鲃试验

利用山涧水开展流水养殖黑脊倒剌鲃,在128m2水泥池中放养规格为10-11尾/kg的鱼种1042kg(10560尾),养殖密度82尾/m2.经271d养殖,收获平均体重511g的倒剌鲃商品鱼5039kg,净产量3997kg;饵料系数2.58,养殖成活率93.34%,净单产31.24kg/m2,利润119.05元/m2,投入产出比为1∶1.78,取得较好的经济效益.     

水晶巴丁鱼的工厂化健康养殖试验

北京市朝阳水产科技园于2004年在工厂化养殖车间进行了水晶巴丁鱼养殖试验.试验池的容积均为36m3,放养密度为54尾/m3.经122天的饲养,水晶巴丁鱼体重从75g长至735g,平均成活率96.3%,产量为38.2kg/m3,平均饵料系数为1.48,平均净收入为262元/m3,平均投资回报率(ROI)为75%.本示范试验的结果表明工厂化养殖水晶巴丁鱼具有生长速度快、饵料系数低、商品鱼规格整齐等特点.     

漳州破灶屿网箱养殖区斜带髭鲷无公害养殖试验

本文描述了2002年12月~2004年1月间在龙海破灶屿网箱养殖区开展的斜带髭鲷无公害养殖试验。根据国家已建立的养殖用水水质、养殖环境和产品无公害标准规定的项目,对养殖生产过程的水域环境和产品进行检测;在养殖生产过程中,以无公害为目标,改进生产工艺。结果表明,龙海破灶屿网箱养殖区养殖环境符合无公害标准;从2003年3月19日~12月15日,将平均体长5.9 cm/尾、平均体重4.0g/尾的鱼苗饲养至平均体长24.9 cm/尾、平均体重420.9g/尾的规格,养成成活率60.1%,使用湿性颗粒饲料的饵料系数为5.2;养成产品符合无公害标准。     

深水网箱高体(鱼师)养殖试验报告

通过对均重1 225 g的大规格高体(鱼师)苗种进行252天的深水网箱养殖,高体(鱼师)的平均体重由1 225 g增至3 350 g, 共收成鱼5 521尾,养殖成活率92.02%,杂鱼饵料系数7.76。     

哲罗鲑的集约化流水养殖

本文对利用泉水集约化养殖哲罗鲑的生长情况、饵料系数、养殖成活率、病害防治进行了总结,并进行了养殖密度和饲料对比试验.经过323d的养殖,哲罗鲑从初始时的1.59g/尾增长到1020g/尾,达到了上市标准,养殖成活率84.84%,饵料系数0.86;密度和饲料实验表明放养800尾/池的哲罗鲑能够获得较好的效果,且投喂进口饲料的哲罗鲑饵料系数0.92,每Kg鱼饲料成本9.05元,投喂国产饲料的哲罗鲑饵料系数1.05,每Kg鱼饲料成本7.66元;影响哲罗鲑的主要疾病是小瓜虫病、烂鳃病和出血病,要提早预防.     

山女鳟适温养殖生产性能观测试验

在年均水温12℃的适温试验区进行性了生产山女鳟养殖试验。0.3 g的苗种饲育270 d,育成尾重61.2 g当龄鱼种,育成率73.2%,单产21.54 kg/m~2,饵料系数1.21。尾重64.2 g的当龄鱼种饲育235 d,育成尾重247.9 g的成鱼,育成率80.3%,饵料系数1.3,单产25.7 kg/m~2。     

在循环养殖系统中添加微生态制剂去除氨氮和亚硝酸氮的试验

利用活菌制剂,以闭路内循环方式净化水质,养殖点带石斑鱼。试验结果表明:3种活菌制剂对NH4 -N的降解率分别为:NMX菌39.0%,科恩菌30.5%,EM菌20.4%;对NO2--N的降解率分别为:NMX菌45.7%,EM菌40.4%,科恩菌13.6%。活菌制剂不仅能调节水质,而且还能促进养殖个体的生长,提高饵料转化率,NMX菌、科恩菌和EM菌试验组日增重分别为5.5 g/尾、5.1 g/尾、4.9 g/尾,而对照组为3.9 g/尾;相应饵料系数分别是1.00、1.02、1.02,对照组为1.06。     

北方内陆水库网箱养殖香鱼(plecoglossus Altivelis)试验

采用活水运输,在石梁河水库网箱养殖香鱼,4只网箱养殖香鱼的密度分别为2500尾、2000尾、1500尾、1500尾,通过对养殖网箱的饵料管理、水质调控、病害防治等,香鱼苗运输14h,运输成活率100%;每只网箱产平均规格81g/尾的商品鱼分别为52.5kg、43.3kg、100.2kg、102.6kg;养成成活率分别为39.2%、47.5%、89.4%、92.6%;养成的平均饵料系数为1.75。     

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).     

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.     

Influence of the antibacterial herbs, Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia on the survival, growth and bacterial load of Penaeus monodon post larvae

The indiscriminate use of antibiotics and chemicals in shrimp hatcheries has led to biomagnification and that in turn could lead to rejection of a whole consignment. The application of the bioencapsulation technique as a tool for curative treatment in shrimp larvae was investigated. Herbs having antibacterial properties such as Solanum trilobatum, Andrographis paniculata and Psoralea corylifolia (methanolic extracts) were bioencapsulated in Artemia and fed to Penaeus monodon post larvae PL 1–25. The post larvae were reared in a medium inoculated with pathogenic bacteria such as Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Vibrio sp. Post larvae reared in the non-inoculated water and fed with non-enriched Artemia exhibited 90% survival, highest specific growth rate (12.43%) and reduced bacterial load. P. monodon reared in the bacterial inoculated water and fed with the non-enriched Artemia exhibited the lowest survival (10–30%), specific growth rate (8.42–9.1%) and increased bacterial load (2.86 × 10³ to 3.76 × 10⁵ cfu/g). The methanolic extracts of the herbs helped to increase survival and specific growth rate and reduced bacterial load in the P. monodon culture system. Among the three herbal extracts, P. corylifolia enriched Artemia fed post larvae showed the tendency to higher survival (>50%), growth rate (11.5 averaged) and low bacterial load (1.12 × 10⁵ cfu/g). This revised version was published online in August 2006 with corrections to the Cover Date.