苏氏圆腹Mang人工繁殖与育苗技术

苏氏圆腹Mang经4冬龄培育达性成熟，人工催产，雌雄1：1配组，多种激素混合使用，共催产亲鱼36组，产卵22组、2500万粒。孵出鱼苗500万尾，最高受精率80％，最高孵化率70％。提高育苗成活率是技术研究重点。     

太阳鱼人工杂交繁殖技术研究

利用人工催产、自然产卵受精技术,对30组蓝鳃太阳鱼(♂)和绿鳃太阳鱼(♀)亲鱼成功地进行人工杂交繁殖试验。在第2次注射催产剂36h后亲鱼开始产卵,4d后产卵结束,共产卵9组,产卵率30%,产卵4.95万粒,受精卵约4万粒,受精率约82.2%。经38~50 h孵化,出苗3.4万尾,孵化率85%。获3 cm苗种2.5万尾,成活率73.5%     

乌鳢规模化繁育技术

2000年6月催产50组成熟亲鱼，网箱静水孵化，共产卵89．5万粒，受精度90％，孵化率98％，培育成3－4cm的鱼种48．3万尾，总投入19480元，产出12．435万元，投入产出比为1：6．38。     

乌鳢人工繁殖试验初探

１９９６年５月２８日，选择１７组乌鳢亲鱼，在孵化槽、产卵池进行人工催产孵化。用轮叶黑藻、水荷叶作鱼巢，一次注射ＤＯＭ加ＬＲＨ－Ａ，催产率、受精率、孵化率分别为１００％、８２．９％、７１．７％。共出苗２０．８万尾。     

加州鲈人工繁殖技术

采用平均体重为0.5kg的加州鲈（Micropterus salmoides)亲鱼雌雄各221尾（221对），人工催产3d后开始产卵，经40d共产卵988批，889.2万粒，出苗711.4万尾，孵化率80%，经20-30d的培育共获2-5cm的幼鱼370万尾，居活率52%，结果表明：加州鲈具有极强的繁殖力；其卵母细胞具有分批成熟，分批产卵的习性；加州鲈亲鱼的产卵量与卵母细胞成熟度有关，与温度无关。     

唇(鱼骨)人工繁殖和鱼苗培育初步研究

对唇(鱼骨)(Hemibarbus labeo)的亲鱼培育、人工繁殖、孵化和鱼苗培育等技术进行了初步研究.试验结果表明:唇(鱼骨)野生亲本在池塘条件下经人工驯养可达性成熟;在水温19.0～21.0 ℃时一次性注射LHR-A2、HCG和DOM混合催产剂,其效应时间18～21.5 h;2005～2006年采用人工催产、自然产卵及人工授精、流水孵化、豆浆法培育鱼苗等方法,共催产雌鱼44尾,平均催产率81.5%,共计产卵45.7万粒,平均受精率82.6%,孵化率77.4%,共孵出鱼苗24.5万尾.鱼苗经25～30 d豆浆法培育后可达3 cm以上,平均成活率为65.5%,共培育夏花15.1万尾.     

花hua人工繁殖技术的研究

2000—2002年进行人工催产获得成功，利用养殖的子代作为亲本进行人工繁殖，共催产942组，产卵828万粒，受精率83．9％，出苗568万尾，孵化率81．8％，为花hua繁育探索了一条新途径。     

使用LRH类似物及衍生物催产家鱼试验

在四川省农科院的协作下，我站于今年5月6日至7日用四川省农科院生产的LRH类似物催产鲢鱼1组，产卵70万粒，鳙鱼1组，产卵65万粒，受精率90％。用LRH类似物的衍生物催产草鱼3组，产卵300万粒，受精率80％，两种新催产剂均获成功，效果良好。     

乌鳢人工繁殖及苗种培育试验

进行了乌鳢人工繁殖及苗种培育试验，采取强化培育亲鱼，塑料大棚水泥池催产孵化，水泥池和土池培育鱼种以及泼洒药液等技术措施，结果；５０组亲鱼共产卵１５０万粒，平均受经率７４．５８％。孵出鱼苗１１３万尾，平均成活率４７．３２％，育成鱼种５１．２万尾。试验证明：催产孵化以６月中旬至７月上旬为宜，孵化最适水温为２３－２６℃。认鉴定认为，试验结果达省内先进水平。     

青鱼人工繁殖试验

用高效催产合剂人工催产青鱼5组，雌雄比1：1。总剂量为LRH－A285μg/kg RES15mg/kg。产卵率为80％，受精率为43％，孵化青鱼苗30万尾。     

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).     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

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.