尖吻鲈温室水泥池饲养试验

为摸索出一套尖吻鲈温室淡水池饲养技术，在温室水泥池内进行了饲养试验。试验结果：1．平均体重189g的鱼种，经过近4个月的饲养，平均规格达到706．4g，饲料系数1．25，养成成活率97．5％；2．尖吻鲈的养殖优势十分明显，集中表现在生长速度快、饲料系数低、抗病能力强、单位面积养殖产量高等方面。     

Nucleotide Degradation Profiles of Iced Barramundi (Lates calcarifer) and Nile Perch (Lates niloticus) Muscle

Adenine nucleotides and their related compounds were determined in muscle extracts from two species of fish that were stored in ice after thawing. The fish were the closely related species, Australian barramundi (Lates calcarifer) and Kenyan Nile perch (Lates niloticus) which had different process histories. For all samples, adenine nucleotides did not exceed 6% of the total nucleotide pool. Inosine monophosphate (IMP) decreased steadily with storage. Hypoxanthine (Hx) was the major product of adenosine triphosphate (ATP) degradation in both barramundi and Nile perch, showing a steady increase with days of iced storage. The Hx level did not reach a maximum during the 9d storage period. The K-value also increased regularly with time of storage and for the later stages (i.e., 7 and 9d) and was significantly different (P < 0.01) for the species. The iced storage life of these typical samples of barramundi and Nile perch was estimated to be 3d after thawing using a K-value of < 30% to indicate excellent quality. Despite the differences in process history the nucleotide profiles were remarkably similar during storage. This precludes the use of nucleotide levels as a means of differentiating between these species.     

Dietary butyric acid improved growth,digestive enzyme activities and humoral immune parameters in Barramundi (Lates calcarifer)

A six‐week feeding trial was conducted to determine the effect of butyric acid (BA) inclusion in diet on performance of Barramundi (Lates calcarifer). Fish (12.0 ± 0.2 g) were fed with four experimental diets contained 0.0 (control), 2.5, 5.0 and 10.0 g BA/kg in triplicate. Fish fed on 5 and 10 g BA/kg diets had higher growth and total alkaline protease and lipase activities than the other treatments. Fillet protein content in BA‐supplemented groups was higher than the control. Liver catalase activity was highest in 2.5 g BA/kg group compared with the other groups. The values of liver superoxide dismutase activity and serum total protein concentration in 5 and 10 g BA/kg treatments were higher than those in the control (p < .05). Moreover, the highest and the lowest levels of serum lysozyme activity were noticed in the 10 g BA/kg and the control groups, respectively (p < .05). Also, the highest respiratory burst activity was observed in fish fed 5 g BA/kg feed. Supplementing diet with 2.5 or 5 g BA/kg resulted in higher serum haemolytic activity in fish compared with the other groups. The number of red and white blood cells increased in fish fed BA‐supplemented diets compared with the control (p < .05). In conclusion, the results of this study showed inclusion of BA at 5 g/kg diet in L. calcarifer juveniles improved growth and upgraded the general health condition by enhancing fish antioxidant enzyme activities and haemato‐immunological responses.     

尖吻鲈仔、稚鱼异速生长研究

以16日龄尖吻鲈(Lates calarifer)为仔、稚鱼发育的区分节点,采用Auto CAD 2014软件对尖吻鲈(孵化后1~36 d)关键器官进行测量和分析。研究发现,在尖吻鲈仔、稚鱼的感觉、呼吸、摄食和游泳等重要器官分化的过程中,均表现出异速生长现象。头部器官中,吻长、口宽在仔、稚鱼期表现出生长速率不同的正异速生长;眼径在仔鱼期为等速生长,稚鱼期转化为负异速生长;仔鱼期的头高为正异速生长,稚鱼期转为负异速生长。在躯干部分器官中,头长在仔、稚鱼阶段均为快速生长,体高及躯干长为等速生长。游泳器官中,仔鱼期,尖吻鲈胸鳍保持等速生长,稚鱼期转为正异速生长;尾鳍在仔鱼期为负异速生长,稚鱼期转化为等速生长,而稚鱼期起始分化的背鳍、臀鳍、腹鳍为快速生长。     

人工海水培育尖吻鲈Lates calcarifer(Bloch)稚幼鱼的生长特性

对尖吻鲈Lates calcarifer(Bloch)稚鱼，早期幼鱼进行人工海水培育生长特性研究结果，个体均全长0.83cm，均重0.006g，的稚鱼经室内水池和室外土池的47d培育，终均全长5.16cm，均重2.15kg；全长日均增长率3.89%，与培育时间的关系式为L=0.8511e^0.0367d；体重日均增长率12.51%，与培育时间的关系式为W=0.0093e^0.1121d；全长与体重的回归方程为W=0.0168L^2.8899，幂指数b接近3，表明体重与全长的立方呈正相关，属于均匀生长型。     

Immune Response and Disease Resistance of Barramundi,Lates calcarifer (Bloch), Offered Diets Supplemented with Replete Levels of Tryptophan or Whey

A basal diet containing 45% protein, 10% lipid, and 1.95% tryptophan (Trp) was formulated, and then supplemented with crystalline Trp (0, 0.1, 0.5, and 1% of the diet) or whey (16.9%) to evaluate the physiological effects of juvenile (initial weight: 0.57 ± 0.15 g) barramundi over a 58‐d rearing period. Significant reductions in growth and feed intake were observed in fish offered diets supplemented with Trp as compared to those offered the basal diet or the whey diet. Brain serotonin increased in fish fed the 1% Trp and whey diets albeit a decrease in cannibalism was not observed. Phagocytic activity, and Mx gene expression in spleens were not significantly changed among all groups. There were significant increases in lysozyme activity in the 1% Trp and whey groups, respiratory burst in the whey group, and Mx gene expression in head kidneys in the 1% Trp group 12 h after nerve necrosis virus (NNV) injection and in the whey 12 group and 24 h after NNV injection. Cumulative mortalities of fish fed the whey diet were significantly lower than those of fish fed the basal diet after Aeromonas hydrophila infection, but not Trp groups. Based on these results, diets supplemented with whey had reduced mortality when challenged with A. hydrophila and consequently function as an immunostimulant.     

池养尖吻鲈和花鲈的生长特性

尖吻鲈（Ｌａｔｅｓｃａｌｃａｒｉｆｅｒ）、花鲈（Ｌａｔｅｏｌａｂｒａｘｊａｐｏｎｉｃｕｓ）为河口性鱼类,可作为池塘养殖的对象。尖吻鲈的适宜生长水温为２５℃～３４℃,快速生长年龄在Ⅰ～Ⅱ龄;花鲈在珠江口地区一年四季均能生长,快速生长年龄在Ⅲ～Ⅳ龄。应用ＶｏｎＢｅｒｔａｌａｎｆｙ方程求得它们在人工饲养条件下体长、体重生长方程：尖吻鲈Ｌｔ＝７０６．５５５３［１－ｅ－０．５１２８（ｔ＋０．２０３２）］,Ｗｔ＝６５５４．４６４９［１－ｅ－０．５１２８（ｔ＋０．２０３２）］３．０３３５;花鲈Ｌｔ＝８８７．４９５８［１－ｅ－０．４０２５（ｔ＋０．０２０９）］,Ｗｔ＝１０８８２．１８８４［１－ｅ－０．４０２５（ｔ＋０．０２０９）］３．１４２７。它们的体重生长拐点分别位于１．９６和２．８２龄处。商品鱼的合理起捕时间应选在生长转折点。参照生物学指标,珠江口地区池养尖吻鲈、花鲈的上市商品鱼应为Ⅰ～Ⅱ龄和Ⅲ～Ⅳ龄,这不仅符合经济原则,也适应当地的消费习惯。     

Mortality from scale drop disease in farmed Lates calcarifer in Southeast Asia

In Southeast Asia, a new disease called scale drop disease (SDD) caused by a novel Megalocytivirus (SDDV) has emerged in farmed Asian sea bass (Lates calcarifer) in Singapore, Malaysia and Indonesia. We received samples from an Eastern Thai province that also showed gross signs of SDD (loss of scales). Clinical samples of 0.2–1.1 kg L. calcarifer collected between 2016 and 2018 were examined for evidence of SDDV infection. Histopathology was similar to that in the first report of SDDV from Singapore including necrosis, inflammation and nuclear pyknosis and karyorrhexis in the multiple organs. Intracytoplasmic inclusion bodies were also observed in the muscle tissue. In a density‐gradient fraction from muscle extracts, TEM revealed enveloped, hexagonal megalocytiviral‐like particles (~100–180 nm). By PCR using primers derived from the Singaporean SDDV genome sequence, four different genes were amplified and sequenced from the Thai isolate revealing 98.7%–99.9% identity between the two isolates. Since viral inclusions were rarely observed, clinical signs and histopathology could not be used to easily distinguish between SDD caused by bacteria or SDDV. We therefore recommend that PCR screening be used to monitor broodstock, fry and grow‐out fish to estimate the current impact of SDDV in Southeast Asia and to prevent its spread.     

Effect of dietary saturated and monounsaturated fatty acids in juvenile barramundi Lates calcarifer

Barramundi (Lates calcarifer), a catadromous teleost of commercial interest, perform well when fed a wide range of dietary oils. However, the range of alternative oils now being explored is typically rich in saturated and monounsaturated fatty acids (SFA and MUFA). In this study, the response of juvenile barramundi (47.0 g per fish initial weight) fed isolipidic and isoenergetic diets with 82 g kg^?1 added oil was tested. The experimental test diets had a 2 : 1 or 1 : 2 ratio of SFA to MUFA (SFA‐D and MUFA‐D, respectively) compared to a control diet (CTRL‐D) fed for 8 weeks. The diets containing mostly olive oil (dietary MUFA‐D) and mostly refined palm oil (dietary SFA‐D) did not impact the growth performance or feed utilization parameters of the barramundi. The in vivo beta‐oxidation activity was consistent with the dietary fatty acid composition, with the most dominant FA being heavily beta‐oxidized. Together, the in vivo whole‐body mass balance of fatty acids showed that n‐3 long‐chain polyunsaturated fatty acids (LC‐PUFA) were most efficiently utilized in the SFA‐D‐ and MUFA‐D‐fed fish. This study provides evidence that additional dietary MUFA and SFA are suitable lipid classes for juvenile barramundi and they are both equally efficient at sparing LC‐PUFA from an oxidative fate.     

低氧水体对尖吻鲈Lates calcarifer(Bloch)头肾巨噬细胞(Head-kidney macrophage)活性的影响

尖吻鲈在水体中含氧量约3.0mg/L状态下(实验组)养殖3天,其吞噬百分率(PA)和吞噬指数(PI)与对照组(含氧量约6.0mg/L)相比无显著变化(P>0.05);在第6天和第9天,实验组的PA和PI比对照组有明显降低(P<0.05);在第12天,实验组与对照组间的PA和PI差异达到极显著(P<0.01)。实验的前6天,实验组与对照组间的动物头肾NBT阳性巨噬细胞数目基本相等;而在第9天后,实验组动物的头肾NBT阳性巨噬细胞数目显著减少(P<0.05)。     

Replacement of fishmeal with commercial soybean meal and EnzoMeal in juvenile barramundi Lates calcarifer

This study investigates the impact of fishmeal replacement by soybean meal (SM) and improved SM known as EnzoMeal (EZ) on fish growth performance. The SM and EZ were used in five experimental diets: fishmeal (600 g/kg) as the control diet, 50% fishmeal replaced with soybean meal (SM50), 50% fishmeal replaced with EnzoMeal (EZ50), 100% fishmeal replaced with soybean meal (SM100) and 100% fishmeal replaced with EnzoMeal (EZ100). Fish in the control group gained the most weight, followed by those under the SM50 and EZ50 diets, while the least weight gain was observed in fish fed the SM100 and EZ100 diets. The specific growth rate (SGR) was higher in the control, but was not different between fish fed SM50 and EZ50, or between SM100 and EZ100. The highest feed intake occurred in the control but decreased sequentially from fish fed SM50 to fish fed EZ50, EZ100 and SM100. Protein digestibility was best in SM50, poorest in EZ100, but no difference between the control, EZ50 and SM100 diets. This study indicates that EnzoMeal, containing high crude protein (56%), is a potential source of plant meal to replace fishmeal in the barramundi diet, but low feed intake is a challenge when EnzoMeal is >300 g/kg.     

Ankylosing spondylosis in the giant perch, Lates calcarifer (Bloch)

Abstract. A disease of the vertebral column is described in three adult wild-caught Lates calcarifer (Bloch) from the Northern Territory, Australia. It is characterized by the deposition of bone in the intervertebral space thus fusing the vertebrae, and the development of a thick gelatinous mass of loose connective tissue around the affected part of the vertebral column. Though a Clostridium sp. was isolated from one fish, it was not thought to be the primary cause.     

Detection of betanodavirus in juvenile barramundi, Lates calcarifer (Bloch), by antigen capture ELISA

Betanodavirus infection of fish has been responsible for mass mortalities in aquaculture hatcheries worldwide. Betanodaviruses possess a bipartite single-stranded RNA genome consisting of the 3.1 kb RNA1 encoding an RNA-dependent RNA polymerase and the B2 protein, while the 1.4 kb RNA2 encodes the viral nucleocapsid protein, alpha. A panel of six monoclonal antibodies against the alpha protein of greasy grouper nervous necrosis virus (GGNNV) was developed for use in diagnostics. All antibodies reacted with native and recombinant alpha in immunoblot and indirect immunofluorescence assays. Each of the monoclonal antibodies reacted against discrete regions of the alpha protein, though none reacted with the extreme C-terminal region of the protein. One of the monoclonal antibodies, specific for the K151-T246 region of alpha, was used for the development of an antigen capture ELISA. In this assay we could detect 10(3)-10(4) TCID(50) units of virus derived from infected tissue culture supernatants. Head tissue extracts prepared from experimentally infected barramundi, Lates calcarifer, juveniles were assayed for GGNNV using the antigen capture assay and a clear increase in alpha antigen was detected from 5 to 15 days post-challenge. The assay thus represents a useful method for field-based detection of betanodavirus in fish hatcheries.     

Cost benefit of hatchery-reared barramundi, Lates calcarifer (Bloch), in Queensland

Abstract. Recreational fishing for barramundi, Lates calcarifer (Bloch), is a major contributor to the economy of Queensland, generating an estimated $A 8 to $A 15 million per annum. The Queensland Department of Primary Industries is investigating the feasibility of enhancing barramundi populations with fish produced in fish hatcheries. Cost benefit analysis of the Department's stocking of baaamundi in Lake Tinaroo indicates that each dollar spent on the programme generates a potential $A 31 of economic benefit to the Queensland economy.     

Caspase-dependent induction of apoptosis in barramundi, Lates calcarifer (Bloch), muscle cells by grouper iridovirus

We recently reported that grouper iridovirus (GIV) can induce apoptosis in barramundi, Lates calcarifer , muscle (BM) and swim bladder (BSB) cell lines. In this paper, we further characterize the molecular mechanism underlying apoptotic death in BM cells triggered by GIV. DNA-laddering and apoptotic cells were observed in BM cells infected with UV-irradiated or untreated GIV but was absent in cells infected with heat-inactivated GIV, indicating the involvement of viral protein in the apoptosis event. In GIV-infected BM cells, the conversion of procaspase-3 to caspase-3 was evident and the level of caspase-8 and -9 increased as early as 30 min post-infection. When treated with a pancaspase inhibitor, the GIV-induced apoptosis event was abolished. These observations indicate that GIV-induced apoptosis is caspase-dependent, and that both the external and internal routes in the caspase-dependent pathway are likely involved in the apoptosis process.     

Isolation and partial characterization of Asian sea bass (Lates calcarifer) Vitellogenin

A study was conducted to isolate, partial characterize Asian sea bass (Lates calcarifer) vitellogenin (vtg). Two-year-old juvenile L. calcarifer (n = 10) were given three intraperitoneal injections of 17-β estradiol (E₂) at a dose of 2 mg/kg body weight to induce vitellogenesis. Blood was collected 3 days after the last injection, and plasma was purified through gel filtration chromatography. A broad single symmetrical peak consisting of vtg molecule was produced. Protein concentration was 0.059 mg/ml as determined by Bradfrod assay using bovine serum albumin as a standard. The protein appeared as one circulating form in Native PAGE considering the dimeric form of putative vtg with molecular weight of 545 kDa. In SDS-PAGE under reducing conditions, two major bands appeared at 232.86 and 118.80 kDa and minor bands at 100.60, 85.80 and 39.92 kDa, respectively. The purified vtg was used to generate a polyclonal antibody, and the specificity of antibody was assessed by Western blot analysis. Two major bands were immunoreacted, but no cross-reactivity was observed with plasma from non-induced males. The protein was characterized as phosphoglycolipoprotein as it positively stained for the presence of lipid, phosphorus and carbohydrate using Sudan Black B, methyl green and periodic acid/Schiff reagent solution, respectively. The amino acid composition was analyzed by high sensitivity amino acid analysis that showed high percentage of non-polar amino acids (~48 %). The results suggest the potential utilization of vtg as a basis tool to further study about reproductive physiology of this important economical species.