10种甲鱼致病菌对二氧化氯的敏感性测定

测定了二氧化氯对１０种甲鱼致病菌在营养肉汤中的最小抑菌浓度（ＭＩＣ）和在池塘水中的最小杀菌浓度（ＭＢＣ）。结果表明：二氧化氯在肉汤中对病原菌有一定抑菌效果，对其中６种菌的ＭＩＣ小于２５μｇ／ｍｌ；二氧化氯在池塘水中的杀菌效果较理想，对其中７种致病菌的ＭＢＣ小于６．２５μｇ／ｍｌ；以作用３０ｍｉｎ杀菌效果最佳。二氧化氯用于甲鱼病害防治是一种较有前途的药物。     

10种于致病菌对二氧化氯的敏感性测定

测定了二氧化氯对１０种甲鱼致病攻在营养肉汤中最小抑菌浓度（ＭＩＣ）和在池塘水中的最小杀菌浓度（ＭＢＣ）。结果表明：二氧化氯在肉汤中对病原菌有一定抑菌效果，对其中６种菌的ＭＩＣ小于２５μｇ／ｍｌ；二氧化氯在池塘水中的杀菌效果较理想，对其中７种致病菌的ＭＢＣ小于６．２５μｇ／ｍｌ；以作用３０ｍｉｎ杀菌效果最佳。二氧化氯用于甲鱼病害防治是一种较有前途的药物。     

对虾健康养殖问答（三）

28、什么是二氧化氯?如何使用?市面上的二氧化氯有固体和液体。固体二氧化氯为白色粉末，分A、B两药，即主药和催化剂，使用时分别将A、B药分开加水溶化，之后二种溶液混合后稀释，发生化学反应。达到杀菌消毒作用。水剂的稳定性二氧化氯，使用效果更好。     

二氧化氯消毒剂对幼蟹养殖的影响

二氧化氯(ClO2)作为一种生产上常用的水产养殖消毒剂，其杀菌效果显著；而且在24小时内对水质指标具有明显的改善作用，诸如氨氮，亚硝态氮浓度下降等。在不换水的淡水养殖条件下，二氧化氯对于幼蟹的存活率和自然生长影响不大．同时对水质pH值也不会产生较大变动，但是在药物浓度达到5μg/l以上时可以导致幼蟹出现大规模死亡现象。研究表明，二氧化氯的除菌效果较为理想，当浓度达0．5μg/l时除菌率就可以达到95％以上。实际生产上建议使用0．1--0．5μg/l之间的浓度，效果较为理想。     

二氧化氯制剂对湘云鲫的急性毒性试验

二氧化氯制剂是ＣｌＯ2 的稳定剂型 ,由气体ＣｌＯ2溶解于过氧化物稳定剂中而得 ,是目前世界公认并得到世界卫生组织确认的Ａ1级广谱、安全、高效消毒剂。ＣｌＯ2 在室温下是一种黄色或黄绿色气体 ,易溶于水 ,具有极强的氧化性 ,其氧化能力是单质氯的2 6倍 ,杀菌活性强。正是由于ＣｌＯ2 具有杀菌效果好、作用快、持续时间长、杀菌能力受ｐＨ影响小 ,并有一定增氧效果 ,在渔业生产上已广泛使用 ,且用量越来越大 ,被认为是包治百病的良药。二氧化氯制剂究竟有没有毒性 ,毒性如何 ?本文以湘云鲫为对象 ,测试了二氧化氯的毒性。1　试验材料1 1…     

卤虫无节幼体的活体消毒试验

卤虫无节幼体是培育海水苗种食物链的重要一环,针对卤虫卵孵化中高温、高密度造成的无节幼体细菌微生物含量过高从而影响育苗成活率这一问题,进行了杀菌试验,结果表明:随着杀菌时间延长到60 min,使用二氧化氯和复合硖杀菌的卤虫无节幼体活力下降,使用紫外线的卤虫无节幼体活力正常;紫外线照射对卤虫无节幼体暂养水的细菌菌落杀灭效果...     

稳定性粉状二氧化氯对养殖池水中蓝藻的杀灭试验

采用稳定性粉状二氧化氯对养殖池水中蓝藻进行杀灭试验,结果表明,在实验室条件下,0.50mg/L浓度的稳定性粉状二氧化氯就可以部分地杀灭蓝藻,而药物浓度达到1.00mg/L就能将蓝藻全部杀灭,在饲养池水中的使用效果也表明稳定性粉状二氧化氯是一种良好的蓝藻杀灭药物。     

盐酸恩诺沙星与其他四种抗菌药物对水产致病菌的体外抗菌作用

用琼脂平板稀释法测定了盐酸恩诺沙星、盐酸环丙沙星、氟哌酸、米诺沙星和氟苯尼考对常见水产致病菌的最低抑菌浓度(MIC)和最低杀菌浓度(MBC)，结果表明：同一抗菌药物对不同致病菌的抗菌效果存在较大差异，不同抗菌药物对同一致病菌的抗菌效果也存在较大差异。使用4倍MBC的药物浓度对嗜水气单胞菌、温和气单胞菌和非O1-群霍乱弧菌杀菌时间随药物种类和致病菌不同而存在差异。     

非热杀菌技术在生食水产品中的应用研究进展

本文综述了传统生食水产品加工方法的生物性危害、和7种非热杀菌技术对水产品的杀菌作用和对其品质的影响,为非热杀菌技术在即生食水产品加工中的应用提供了参考。其中超高压杀菌技术、辐照杀菌技术、高密度CO2杀菌技术具有良好的杀菌效果,但其对水产品品质的影响因水产品种类、工艺参数等条件的不同而存在差异。高压杀菌技术和高密度CO2杀菌技术在高处理强度下会使鱼类、虾类等出现肉质透明度降低、硬度增加的现象,辐照杀菌技术在高处理强度下则会使水产品产生异味。而稳定态二氧化氯、臭氧杀菌技术、酸性电解水和生物保鲜剂具有良好的减菌、抑菌效果,对水产品品质的影响较小,可用于延长水产品货架期,维持品质。     

二氧化氯和三氯异氰脲酸对鱼类3种致病菌的杀灭试验

对肠型点状产气单胞杆菌，嗜水气单胞菌和柱状曲桡杆菌进行复壮．将分离纯化的3种菌用二氧化氯和三氯异氰尿酸进行抑菌、杀菌效果研究。结果表明：二氧化氯对肠型点状气单胞菌、嗜水气单胞菌、柱状曲桡杆菌的最小抑菌浓度分别是0．17、0、17、0．06μg／mL，最小杀菌浓度分别是0．23、0．23、0．17μg／mL；三氯异氰脲酸对上述3种菌的最小抑菌浓度分别是6．25、12．5、6．25μg／mL，最小杀菌浓度分别是12．5、25．0、6．25μg／mL。     

Effect of temperature on growth and energy budget of juvenile cobia (Rachycentron canadum)

Growth and energy budget of juvenile cobia (initial body weight ∼ 22 g) at various temperatures (23, 27, 31 and 35 °C) were investigated in this study. Maximal ration level (RL_max, %/day) increased as temperature (T, °C) increased from 23 °C to 31 °C but decreased at 35 °C, described as a quadratic equation: RL_max = −0.023T² + 1.495T − 17.52. Faecal production (f, mg g^− 1 day^− 1) increased with increased temperature (T, °C), described as a power function: lnf = 0.738lnT − 0.806. As temperature increased, feed absorption efficiency in dry weight (FAE_d, %), protein (FAE_p, %) and energy (FAE_e, %) all increased first and then decreased, but the variation of feed absorption efficiency was small, with ranges of 89.59-91.08%, 92.91-94.71%, 93.92-95.32%, respectively. Specific growth rate in wet weight (SGR_w, %/day), dry weight (SGR_d, %/day), protein (SGR_p, %/day) and energy (SGR_e, %/day) showed a domed curve relative to temperature (T, °C), described as quadratic equations: SGR_w = − 0.068T² + 3.878T − 50.53, SGR_d = − 0.079T² + 4.536T −59.64, SGR_p = − 0.084T² + 4.783T − 63.08 and SGR_e = − 0.082T² + 4.654T − 60.99, and SGR_w, SGR_d, SGR_p and SGR_e maximized at 28.5 °C, 28.6 °C, 28.4 °C, 28.5 °C, respectively, as calculated from the regression equations. The relationships between feed conversion efficiency in wet weight (FCE_w, %), dry weight (FCE_d, %), protein (FCE_p, %), energy (FCE_e, %) and temperature (T, °C) also took on a domed curve described as quadratic equations: FCE_w = − 0.726T² + 39.71T − 473.8, FCE_d = − 0.276T² + 15.31T − 190.6, FCE_p = − 0.397T² + 22.05T − 277.9 and FCE_e = − 0.350T² + 19.39T − 239.9, and FCE_w, FCE_d, FCE_p and FCE_e maximized at 27.4 °C, 27.8 °C, 27.7 °C and 27.7 °C, respectively, as calculated from the regression equations. Energy budget of juvenile cobia fed satiation was 100C = 5F + 67(U + R) + 28G at water temperature 27 °C and 100C = 5F + 70(U + R) + 25G at water temperature 31 °C, where C is food energy, F is faeces energy, (U + R) is excretion energy and metabolism energy, and G is growth energy.     

Interspecific variations in age and size at settlement of 8 emperor fishes (Lethrinidae) at the southern Ryukyu Islands,Japan

Molecular and otolith analyses were conducted for 173 settlement-stage larvae of emperor fishes (family Lethrinidae) collected by light traps at Ishigaki Island, southern Japan, in July and August (summer season), to (1) present diagnostic DNA markers for identification of lethrinid species and (2) compare the size and age at settlement of each species. PCR–RFLP and direct nucleotide sequencing analyses identified 8 species. Size (standard length, SL) at settlement differed significantly between species; Lethrinus ornatus (mean SL ± SD, 12.8 ± 1.5 mm), L. obsoletus (14.2 ± 0.8 mm) and L. harak (15.8 ± 1.6 mm) settled at a smaller size than L. atkinsoni (17.0 ± 1.3 mm), L. genivittatus (17.3 ± 1.0 mm), L. olivaceus (18.1 ± 0.6 mm), L. nebulosus (18.6 ± 4.2 mm), and L. sp.2 reported by Lo Galbo et al. (J Mol Evol 54:754–762, 2002) (21.7 ± 1.4 mm). Age at settlement tends to increase with settlement size; L. obsoletus (mean age ± SD, 25.6 ± 1.2 days), L. atkinsoni (26.1 ± 2.1 days) and L. ornatus (26.3 ± 2.9 days) were younger at settlement than L. nebulosus (28.4 ± 2.1 days), L. harak (29.2 ± 1.7 days), L. olivaceus (29.5 ± 1.0 days), L. genivittatus (30.5 ± 1.7 days) and L. sp.2 (31.0 ± 2.0 days). Although our study showed interspecific variation in body size and age at settlement among 8 lethrinid species, further seasonal replication is necessary to clarify the general patterns.     

Enhancing rotifer Brachionus calyciflorus population growth with commercial probiotics

The effect of a commercial probiotic (NanoCrusta, Altacrusta, Mexico City, Mexico) on the growth performance of Brachionus calyciflorus Pallas, 1766, was evaluated. In a first approach, probiotics were supplied in four densities (2.0 × 10³, 1.1 × 10⁵, 2.1 × 10⁵ and 2.1 × 10⁶ cells/ml), alone and in combination with Chlorella vulgaris (1 × 10⁶ cells/ml). The test rotifer did not grow on the probiotic alone. However, when probiotics + C. vulgaris were added, the maximum densities (D_max; ind/ml) and population growth rates (r) observed were higher. In the second experiment, probiotics were supplied at five higher densities (2.1 × 10⁶, 4.2 × 10⁶, 8.5 × 10⁶, 1.7 × 10⁷ and 3.4 × 10⁷ cells/ml) with C. vulgaris and a control treatment with only C. vulgaris (probiotic‐free). Treatments supplied with probiotics between 2.1 × 10⁶ and 1.7 × 10⁷ cells/ml showed significantly higher D_max and r than the control treatment. The results showed a positive effect of probiotic bacteria when supplied with C. vulgaris. The best outcome showed a D_max 2.16 times and an r 1.63 times higher than the density of the control treatment. Growth rates were higher in the treatments with probiotics compared to the control. We conclude that application of NanoCrusta is feasible to improve B. calyciflorus production, but the effects need to be tested in larger scales.     

Effect of prebiotic xylooligosaccharides on growth performances and digestive enzyme activities of allogynogenetic crucian carp (<Emphasis Type="Italic">Carassius auratus gibelio</Emphasis>)

The effect of prebiotic xylooligosaccharides (XOS) on the growth performance and digestive enzyme activities of the allogynogenetic crucian carp, Carassius auratus gibelio, was investigated. XOS was added to fish basal semi-purified diets at three concentrations by dry feed weight: diet 1, 50 mg kg⁻¹; diet 2, 100 mg kg⁻¹; diet 3, 200 mg kg⁻¹, respectively. Twelve aquaria (n = 20) with three replicates for each treatment group (diets 1–3) and control treated without XOS were used. Weights of all collected carp from each aquarium were determined at the initial phase and at the end of the experiment, and the carp survival was also determined by counting the individuals in each aquarium. After 45 days, there were significant differences (P < 0.05) in the relative gain rate (RGR), and daily weight gain (DWG) of diets 1–3 were compared with the control. However, the survival rate was not affected (P > 0.05) by the dietary treatments. For enzymatic analysis, dissection produced a crude mixture of intestine and hepatopancreas of each segment to measure. The protease activity in the intestine and hepatopancreas content of fish in diet 2 (487.37 ± 20.58 U g⁻¹ and 20.52 ± 1.93 U g⁻¹) were significantly different (P < 0.05) from that in the control (428.13 ± 23.26 U g⁻¹ and 12.81 ± 1.52 U g⁻¹) and diet 3 (428.00 ± 23.78 U g⁻¹ and 14.04 ± 1.59 U g⁻¹). Amylase activity in the intestine was significantly higher for diet 2 compared to diet 1 and the control. As for amylase in the hepatopancreas, assays showed higher activity in diet 2 (P < 0.05) compared to the rest.     

Rearing of African catfish (Clarias gariepinus) and vundu catfish (Heterobranchus longifilis) in traditional fish ponds (whedos): Effect of stocking density on growth, production and body composition

African catfish (Clarias gariepinus) (initial body weight: 34.8 ± 4.8 g) and vundu catfish (Heterobranchus longifilis) (initial body weight: 39.1 ± 8.2 g) fingerlings were stocked at densities of 4, 6 or 8 fish m^− 3 in traditional fish ponds (whedos) constructed in the floodplain of the Oueme River (South Benin, West Africa), for 70 days from March to June 2005. Fish were fed twice a day with 34% crude protein feed formulated with locally available ingredients. The effects of stocking density were evaluated in growth responses, gross production and body composition. Water quality variables were similar (p > 0.05) in all compartments. Temperature and pH were at the optimum level for fish. Dissolved oxygen ranged from 0.9 to 1.2 mg l^− 1 during the experiment and secchi disc transparency was low (< 14 cm). In both species, growth responses increased with the increasing density, significantly in African catfish stocked at density of 8 fish m^− 3 compared to the other densities (4 and 6 fish m^− 3) but not significantly in vundu catfish. Production data ranged from 3.1 ± 0.5 to 22.8 ± 4.5 t ha^− 1 year^− 1 in African catfish and from 6.1 ± 1.2 to 15.1 ± 3.1 t ha^− 1 year^− 1 in vundu catfish. Production increased with increasing stocking densities but only significantly (p < 0.05) between the density of 8 fish m^− 3 and the other densities. In both species, carcass fat increased with increasing density (p < 0.05) while carcass protein and moisture decreased (p > 0.05). These results are important because they indicate that, as far as growth rate and production are concerned, African catfish is more profitable than vundu catfish for culture at high density in whedo.     

Bacterial flora associated with the giant freshwater prawn Macrobrachium rosenbergii, in the hatchery system

The objective of this study was to understand the microbial flora associated with the hatchery system of giant fresh water prawn, Macrobrachium rosenbergii during an entire rearing cycle. Bacteriological and physico-chemical analysis was done for different samples of water, larvae, and Artemia. The total bacterial load in well water, seawater and inlet water varied from 10¹ to 10⁵ cfu ml^− 1 with higher counts seen in larval rearing tank (LRT) water. The Vibrio count ranged between 10¹ to 10³ cfu ml^− 1. Larval samples harboured a bacterial load of 10⁶ to 10⁷ cfu/10 larvae. The bacterial load in Artemia hatching water ranged from 4.90 × 10⁴ to 5.63 × 10⁶ cfu ml^− 1 while Artemia had a load ranging from 1.08 × 10⁷ to 2.09 × 10⁹ cfu g^− 1. Vibrio count in the LRT water ranged from 10¹-10³ cfu ml^− 1 while the count in larvae ranged from 10² to 10⁴ cfu/10 larvae. The bacterial genera were predominantly Gram-negative and comprised of Aeromonas spp., Pseudomonas spp., Vibrio spp. and Bacillus spp. and non-spore formers (NSF) were the dominant Gram-positive bacteria. This study documents the bacterial flora associated with Macrobrachium hatchery system during a regular normal run. Knowledge of the qualitative and quantitative aspects of bacterial flora in the hatchery would help to understand disturbances, if any, brought about during disease outbreaks.