尖吻鲈幼鱼耗氧率的研究

在不同水温条件下对两种规格尖吻鲈幼鱼的耗氧率进行测定。结果表明:(1)水温和规格对耗氧率有极显著的影响,小规格的明显高于大规格的,分别为0.1028±0.0251mg·g-1·h-1和0.0879±0.0215mg·g-1·h-1;(2)尖吻鲈幼鱼夜间的耗氧率比白天明显要高,分别为0.1109±0.0187mg·g-1·h-1和0.0799±±0.0186mg·g-1·h-1。     

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。     

鸡内金多糖对尖吻鲈幼鱼生长、消化、肠道抗氧化能力和血清生化指标的影响

该研究探讨了鸡内金多糖(Polysaccharide from Endothelium corneum gigeriae galli,PEGG)对尖吻鲈(Lates calcarifer)幼鱼生长、消化、肠抗氧化能力和血清生化指标的影响,以为PEGG在尖吻鲈健康养殖中的应用提供参考依据.在饲料中添加0(对照组)、5(低...     

尖吻鲈、花鲈和大口黑鲈在池塘的集约化养殖

<正> 尖吻鲈又称雷子鱼,是东南亚热带和亚热带国家的经济鱼类,早期生活在海水和咸淡水海区,成鱼可在海水或淡水中养殖。其幼鱼为杂食性,成鱼为肉食性。尖吻鲈在泰国的性成熟年龄为3周龄。花鲈俗称七星鲈,在我国有丰富的天然种苗资源。花鲈为广温近岸浅海凶猛鱼类,喜栖于河口咸淡水区,也生活于淡水,秋末冬初到河口产卵。大口黑鲈俗称加洲鲈,原产美国加里福尼亚洲,是适温较广的肉食性鱼类。在盐度12‰以下的咸淡水和淡水中均可养殖。鱼苗阶段以浮游动物为饵科,成鱼为肉食性。     

Evaluations of lactic acid bacteria as probiotics for juvenile seabass Lates calcarifer

Lactic acid bacteria (LAB) were isolated from adult, wild‐caught and farmed seabass (Lates calcarifer) intestines for evaluation as possible probiotics using the well agar diffusion method. Five LAB isolates (designated as LAB‐1–5) were found to inhibit Aeromonas hydrophila, a known seabass pathogen. Median lethal concentrations (LC₅₀) of A. hydrophila on juvenile seabass were measured in aquaria. Median lethal concentration values of 7.76, 7.47 and 7.26 log₁₀ CFU mL^?1 for 72, 96 and 120 h, respectively, were found. Juvenile seabass (0.6±0.2 g) were cultured in aquaria and fed individual LAB‐1–5 fortified feeds with 7 log₁₀ CFU g^?1 LAB. Seabass fed LAB‐4 fortified feed had significantly greater growth (P<0.05) than fish fed other feeds. Seabass fed LAB‐4 also had greater survival, but this was non‐significant (P<0.05). Challenge tests of LAB‐4 fed seabass with A. hydrophila at ～7 log₁₀CFU mL^?1 yielded significantly greater survival compared with control seabass (P<0.05). Aeromonas hydrophila infections in seabass were confirmed by observing disease manifestation and by immunohistochemistry techniques. LAB‐4 was preliminarily identified using lactic acid analysis, biochemical and physical characteristics. It was further identified using 16S rDNA sequencing. LAB‐4 was identified as Weissella confusa (identity of 99%). GenBank accession number for the 16S rDNA sequence for LAB‐4 was AB023241.     

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.     

Growth trials for polyculture of hatchery-reared juvenile spotted babylon (Babylonia areolata) and sea bass (Lates calcarifer) in a flow-through sea water system

Juvenile spotted babylon (Babylonia areolata) and sea bass (Lates calcarifer) were cultured in 11.5‐m³ indoor rearing tanks supplied with flow‐through of ambient natural sea water over a 120‐day experiment. Each species, stocked at the following densities for the following treatments, was tested with three replicates per treatment: 5000 B. areolata per tank (Treatment 1); 200 L. calcarifer per tank (Treatment 2); and 5000 B. areolata plus 200 L. calcarifer per tank (Treatment 3),. The average growth (length and weight), feed conversion ratio and total production of spotted babylon and sea bass from Treatment 3 were not significantly different from those of Treatment 1 and 2 (P > 0.05). Average survival rates for both spotted babylon and sea bass exceeded 95% for all treatments.     

Genetic variation of Lates calcarifer in Peninsular Malaysia based on the cytochrome b gene

A 312 bp segment of the mitochondrial cytochrome b gene was sequenced from 132 sea bass Lates calcarifer individuals from nine populations across Peninsular Malaysia. Phylogenetic analysis and analysis of molecular variance within and among populations showed no significant geographical structuring. Several populations formed discrete units while others were of mixed populations. The former group suggests a low gene flow among some populations while the latter suggests that widespread translocations have impacted the other wild and cultured local populations. The data from this study have important implications for fishery management, conservation of sea bass stocks and translocation policy for aquaculture and stock enhancement in Peninsular Malaysia.     

Effects of dietary fish oil replacement on growth and carcass proximate composition of juvenile barramundi (Lates calcarifer)

An experiment was carried out to determine the effects of dietary fish oil replacement at an optimal level on the growth and carcass proximate composition of juvenile barramundi or sea bass (Lates calcarifer). Ten fish feeds were formulated to contain iso‐ingredients with theoretically identical dietary lipid levels but with different sources of lipids (fish oil, soybean oil, canola oil and linseed oil) replacing dietary fish oil. Three hundred fish were equally divided into 30 70‐L plastic tanks (three replicate tanks for each treatment). Fish were fed with experimental diets for 40 days within closed recirculating freshwater systems (70 L h^?1, 28°C and 12L:12D). Growth, specific growth rate, food conversion ratio (FCR) and carcass proximate composition were determined. Dietary lipids significantly affected (P<0.05) the growth of the fish. Good growth and low FCR were observed in all treatments. Therefore, fish oils can be partially replaced by vegetable oils to reduce the feed cost. There were no significant differences (P>0.05) in lipid, moisture and protein content in fish carcasses among the group. However, juvenile barramundi showed increasing lipid and moisture content in muscle, whereas decreasing protein content when compared to the initial fish.     

Detection of nodavirus in barramundi, Lates calcarifer (Bloch), using recombinant coat protein-based ELISA and RT–PCR

The coat protein encoded by the nodavirus RNA2 gene originally isolated from greasy grouper, Epinephelus tauvina , was cloned, expressed as a recombinant polyhistidine-tailed fusion protein and characterized by immunoblot analysis. The purified recombinant protein was used to develop an indirect enzyme-linked immunosorbent assay (ELISA) to detect body exudate and plasma antibodies against the coat protein in both experimentally infected and commercial barramundi. In addition, the nucleotide sequence was employed to develop a RT–PCR detection assay based on the T4 region. The results showed that the virus could be detected as early as 3 days post-infection by RT–PCR while antibodies against the recombinant coat protein were detectable on day 6 post-infection. Among 112 commercial barramundi samples collected from October 1999 to April 2000, 9% showed positive ELISA results which were further verified by Western blot.     

光合细菌PS2对尖吻鲈的生长、消化酶及非特异性免疫酶的影响

研究了光合细菌对尖吻鲈（Latescal carifer）的生长、消化酶及血清免疫酶活性的影响。把浓度为8×10^8cfu·mL^-1的荚膜红假单胞菌（Rhodopseudomonas capsulate）的液体制剂分别以0．0％（对照组）、0．5％、1．0％和1．5％的比例添加到饲料中,投喂初始体质量为（10．95±0．25）g的尖吻鲈50d。鱼的增重率、特定生长率、成活率及饲料系数在组间均没有显著性差异（P〉0．05）。肝蛋白酶、肠淀粉酶及胃淀粉酶在1．0％组显著高于对照组（P〈0．05）;肠蛋白酶在1．5％组显著低于1．0％组（P〈0．05）,但试验组与对照组间没有显著性差异（P〉0．05）;幽门垂的消化酶在1．5％组显著高于其他各组（P〈0．05）。血清碱性磷酸酶（AKP）、过氧化物酶（POD）和超氧化物歧化酶（SOD）的活性在组间均没有显著性差异（P〉0．05）。结果表明,该株光合细菌对尖吻鲈的生长及非特异性免疫力没有显著影响,但在1．5％组能显著促进其幽门垂消化酶的活性,在1．0％组显著促进肝蛋白酶及肠和胃淀粉酶的活性。