香鱼嗜水气单胞菌人工染病后血液生理生化指标变化

从患病香鱼的体腔液中分离获得嗜水气单胞菌病原,经培养稀释的菌液,腹腔注射人工感染健康香鱼,出现典型的出血症后,进行血液生理生化指标的测定。结果发现,病鱼红细胞数量为(1.21±0.08)×1012个/L,血栓细胞数量(189.00±5.19)×1012个/L,较健康香鱼红细胞[(2.41±0.16)×1012个/L]、血栓细胞[(380.0±20.00)×1012个/L]呈极显著降低(P0.01),血红蛋白含量呈显著减少(P0.05),而白细胞数量却显著增加(P0.05)。染病香鱼总蛋白为(47.56±2.63)g/L,健康鱼为(49.23±3.06)g/L,经检验无显著差异;而碱性磷酸酶、Cl-、Ca2+等3项血液生化指标值均呈极显著减少(P0.01),乳酸脱氢酶呈极显著增加(P0.01)。     

5种石斑鱼遗传差异的RAPD分析

运用随机扩增多态性DNA（random amplified polymorphic DNA,RAPD）技术对鞍带石斑鱼（Epinephelus lanceolatus）、驼背鲈（Cromileptes altivelis）、棕点石斑鱼（E.fuscoguttatus）、斜带石斑鱼（E.coioides）和鲑点石斑鱼（E.fario）的遗传多样性及系统发生进行了研究。从120个RAPD随机引物中筛选出扩增效果好的引物19个,分别用于5种石斑鱼基因组DNA的扩增。结果显示,5种石斑鱼平均多态性位点比率（P）分别为64.23%,72.61%,60.34%,69.97%,73.94%;个体间平均遗传相似系数（S）分别为0.8238,0.8110,0.8345,0.8277,0.8064;平均遗传距离（D）分别为0.1762,0.1890,0.1655,0.1723,0.1936;平均Nei基因多样性指数（H）分别为0.1189,0.1364,0.1028,0.1439,0.1648;平均Shannon信息指数（Hi）分别为0.1801,0.1992,0.1530,0.2100,0.2434。5个种间的遗传距离（Dxy）在0.3964～0.6085之间。     

Characterization of the digestive tract of wild ayu

ABSTRACT: The gut and gut contents of ayu Plecoglossus altivelis caught in the Ohta River in Hiroshima prefecture, Japan were examined. Relative intestine length (intestine length/body length) was almost constant. Except for relative intestine length, characteristics of the gut of wild ayu were not significantly different from those of cultured ayu. The height of intestinal folds increased and their width declined from stomach to anus. Cyanobacteria ( Homoeathrix sp. and Calothrix sp.) and diatoms ( Cymbella sp., Gomphonema sp., Melosira sp., Navicula sp., and Synedra sp.) were well digested during passage through the gut despite a lack of apparent destruction. In contrast, green algae ( Dictyosphearium sp., Coelastrum sp., and Pediastrum sp.) exhibited little degradation. The pH of stomach contents ranged from 2.8 to 7.4 (mean ± SD = 4.1 ± 1.0), whereas that of the posterior intestine was 7.0–8.5 (7.9 ± 0.4). Gut contents of wild ayu increased with bodyweight, and were more than threefold greater than those of cultured ayu, suggesting that wild ayu compensate for low nutrient content of algae through the continuous ingestion of large quantities of feed organisms.     

Morphological development of eggs, larvae and juveniles of laboratory-reared Ryukyu-ayu Plecoglossus altivelis ryukyuensis

ABSTRACT:   The development of embryos, larvae and juveniles of the Ryukyu-ayu, Plecoglossus altivelisryukyuensis are described based on laboratory-reared specimens.The eggs were spherical, 0.98–1.18 mm (mean 1.06 mm)in diameter with an adherent membrane. The incubation period after fertilizationwas approximately 155 h at a water temperature of 19.7–22.0°C(mean 20.7°C). Newly hatched larvae were 5.0–5.9 mm(mean 5.5 mm) in body length (BL) with 59–62 myotomes.Within 5 days after hatching, the larvae had attained 6.4–8.2 mm(mean 7.8 mm) BL and had completely consumed their yolk.Notochord flexion began at 13.7 mm BL and was completedby 16.3 mm BL. The rudimental dorsal, anal, pelvic andadipose fins appeared at 14.7, 16.3, 21.8 and 21.8 mm BL, respectively.All fin rays reached the same fixed number of adult fish at about28 mm BL. The comb-like teeth began to form at approximately30 mm BL and were fully developed at about 40–50 mm BL.The proportions of P. a. ryukyuensis specimens,which were consistent with adult fish, occurred at approximately40 mm BL.     

驼背鲈室内池塘育苗技术研究

[目的]改进驼背鲈的育苗方法。[方法]选择3龄以上的驼背鲈亲鱼进行海水网箱养殖,用绒毛膜促性腺激素（HCG）和释放激素（LRH—A3）混合悬浊液进行催产。通过向育苗池中定时定量加入高级虾片和EM茵的方法进行驼背鲈的育苗。[结果]驼背鲈仔鱼在水泥池水温22～26℃、盐度28％-32％、pH7．9～8．7的条件下,经30d培育,平均鱼体全长达3．3cm,仔鱼变态发育成幼鱼。[结论]驼背鲈可在室内池塘通过亲鱼人工催产获得受精卵,EM菌＋高级虾片方法是经济有效的驼背鲈育苗方法。     

驼背鲈人工育苗技术初探

选取网箱驯养的野生驼背鲈亲鱼,经过强化培育,采用HCG催熟,网箱中自然产卵受精,采用池塘蓄水和室内玻璃钢水槽培育相结合的方法,成功繁育出驼背鲈3 cm左右鱼苗3万尾,繁育成功的关键技术是亲鱼的驯养和强化,控制好水质,提供适口、营养丰富的开口饵料生物.     

香鱼配合饲料挤压加工工艺优化研究

为了生产出低污染、高转化率的环保型香鱼沉性挤压饲料,以沉性香鱼配合挤压饲料膨化度、近似密度和水中稳定性为重要特性指标,采用单因素和正交试验研究了物料含水率、螺杆转速和螺杆温度对其挤压工艺和饲料特性的影响.结果表明:物料含水率、螺杆转速和螺杆中、后部温度均影响饲料膨化度、近似密度和水中稳定性,正交方差分析显示,螺杆后部温度对近似密度有显著影响.通过单因素和正交试验确定香鱼配合饲料挤压工艺条件为:物料含水率30％、螺杆转速90 r/min、螺杆后部温度90℃,此条件下挤压饲料产品的近似密度最大,水中稳定性也较好,能很好地满足香鱼的摄食要求.