Bioaccumulation and depuration of chromium in the selected organs and whole body tissues of freshwater fish Cirrhinus mrigala individually and in binary solutions with nickel

Contamination of aquatic ecosystems with heavy metals has been receiving increased worldwide attention due to their harmful effects on human health and other organisms in the environment. Most of the studies dealing with toxic effects of metals deal with single metal species, while the aquatic organisms are typically exposed to mixtures of metals. Hence, in order to provide data supporting the usefulness of freshwater fish as indicators of heavy metal pollution, it has been proposed in the present study to investigate the bioaccumulation and depuration of chromium in the selected organs of freshwater fingerlings Cirrhinus mrigala, individually and in binary solutions with nickel. The results show that the kidney is a target organ for chromium accumulation, which implies that it is also the ＂critical＂ organ for toxic symptoms. The results further show that accumulation of nickel in all the tissues of C. mrigala is higher than that of chromium. In addition, the metal accumulations of the binary mixtures of chromium and nickel are substantially higher than those of the individual metals, indicating synergistic interactions between the two metals. Theoretically the simplest explanation for an additive joint action of toxicants in a mixture is that they act in a qualitatively similar way. The observed data suggest that C. mrigala could be suitable monitoring organisms to study the bioavailability of water-bound metals in freshwater habitats.

Antimicrobial ability and growth promoting effects of feed supplemented with probiotic bacterium isolated from gut microflora of Cirrhinus mrigala

The present studies were conducted to isolate, select, identify and characterize gut bacteria as antimicrobial and growth promoting agent for the feed of economically important fish Cirrhinus mrigala. Intestinal microflora were isolated, counted, and identified, and their in vitro antibacterial properties were determined. The results have revealed that occurrence of Gram-negative rods was around 75% and of Gram-positive rods was 25%. Among the isolates Gram-positive were maintained in nutrient agar slants at 4℃. Of these, eight strains were replica-plated on agar seeded with Aeromonas hydrophila and only one strain CM2（C. mrigala 2） exhibited antibacterial properties in vitro showing inhibition against fish pathogen by well diffusion assay. This isolated strain was identified as Bacillus cereus. This bacterium was mass cultured and incorporated in the pelleted diet（40% protein and 18 k J g^–1 gross energy） of C. mrigala to investigate its effect on growth performance, digestibility, nutrient retention and activities of digestive enzymes. The results of feeding trial revealed significantly（P〈0.05） high growth performance in terms of specific growth rate, growth percent gain in body weight（BD）（272.4±1.5）%, high apparent protein digestibility（（79.9±0.30）%） and low food conversion ratio in the group of fishes fed on diet containing B. cereus in comparison to the fishes fed on diet without probiotics. The carcass composition also revealed high accumulation of proteins（（15.28±0.15） g 100 g^–1） in fishes fed on diet containing probiotics. Intestinal enzyme activities of protease, amylase and cellulase were also significantly（P〈0.05） high in the group of fishes fed on diet supplemented with probiotics indicating the extracellular enzyme production by B. cereus. These results indicate that probiotics stimulate the digestion through the supply of digestive enzyme and certain essential nutrients to animals. Also significantly（P〈0.05） low excretion of metabolites, i.e., ammonia excretion and phosphate production（mg kg^–1 BW d^–1） was observed in the fishes fed with probiotic based diets. Thus, B. cereus appears to be a promising candidate for ptobiotic applications which can enhance growth performance and nutrient retention in C. mrigala.

ESTIMATION OF VOLATILE CONSTITUENTS IN THE FISH FLESH FROM WILD AND FARMED CIRRHINA MRIGALA AND CYPRINUS CARPIO

Analysis of fish meat using gas chromatography is described.Flavor is the sensation arising from the interplay of the signals of sensing smell, taste and irritating stimuli from food stuff.For human, flavor and nutrition are inseparable.In fish, trace amount of volatile organic compounds (VOCs) are the major compounds to affect consumer’s preference, which are produced during storage and spoilage.In the present study, volatile compounds were extracted by Likens-Nickerson concurrent distillation apparatus from wild and farmed Cirrhina mrigala and Cyprinus carpio. The quantitative and qualitative estimation of volatiles was made by gas chromatography.Wild and farmed fish of different fish sizes were compared for these compounds (appearing in the form of peaks), which were identified from their retention time by comparing with the standards.Fifteen major VOCs were found in these species which included hexadecane, 3-octanol, hexanal, decane, 3-hexene-1-ol, 2-undecanone, 2-heptanone, butanal, 2-nonanone, 1-heptanal, furaldehyde, 3-methyl-1-butanal, trans-3-hexene-1-ol, octanal and decanal.These compounds varied qualitatively and quantitatively in both wild and farmed fish of different fish sizes.

受短期饥饿胁迫下麦瑞加拉鲮鱼(Cirrhina mrigola)幼鱼的生长、肌体组分及其内脏消化酶活力的变化特征

以麦瑞加拉鲮鱼幼鱼为实验动物,进行短期饥饿对其生长、肌体组分及内脏消化酶活力的影响实验。结果表明,随着饥饿时间的延长,麦瑞加拉鲮鱼幼鱼各生长参数观测值,体内粗脂肪、碳水化合物和粗蛋白的含量以及能值均逐渐减小或减少;实验期间体内各组分的同期相对损失率以粗脂肪和碳水化合物为最高,且粗脂肪降幅高峰的出现时段总早于碳水化合物,而粗蛋白的消耗量和损失率则一直处于较低的水平。淀粉酶活力的损失量均高于同期其他消化酶,蛋白酶活力在13—16天间出现反弹现象,其第16天的酶活力值与实验起始值相当。

4种消毒剂对麦瑞加拉鲮鱼幼鱼的急性毒性研究

2005年7～8月在浙江省余姚市青港野生苗种场，以体长（4．92±0．44）cm的麦瑞加拉鲮鱼幼鱼Cirrhina mrigola为实验动物，开展鱼安、二溴海因、菌毒清和溴氯海因等4种消毒剂对该鱼幼鱼的急性毒性试验。结果表明，鱼安、二溴海因、菌毒清和溴氯海因对麦瑞加拉鲮幼鱼的急性致毒时限为8h；鱼安对麦瑞加拉鲮鱼幼鱼2、4、6、8h的半致死浓度分别为16．070、16．267、15．780和15．687mg／L；二溴海因对麦瑞加拉鲮鱼幼鱼2、4、6、8h的半致死浓度分别为42．750、41．673、41．171和40．283mg／L；溴氯海因对麦瑞加拉鲮鱼幼鱼2、4、6、8h的半致死浓度分别为19．066、16．565、17．676和16．966mg／L；菌毒清对麦瑞加拉鲮鱼幼鱼2、4、6、8h的半致死浓度分别为6．267、5．785、5．451和5．451mg／L。麦瑞加拉鲮鱼幼鱼对鱼安、二溴海因、溴氯海因和菌毒清8h安全质量浓度分别为1．569、4．028、1．697和0．545mg／L，4种常用消毒剂的毒性大小依次为菌毒清、鱼安、溴氯海因和二溴海因。最后，还就鱼安、二溴海因、菌毒清和溴氯海因对麦瑞加拉鲮鱼幼鱼有效急性致毒实验时间的确定及其急性致毒效应特征，药物毒性蓄积系数MAC公式的解释与应用、诸药物间的致毒效果比较及其安全使用等进行了探讨．

2种农药对麦瑞加拉鲮鱼幼鱼的急性毒性

以体长(5.56±0.31)cm、体质量(2.67±0.40)g的麦瑞加拉鲮鱼幼鱼为试验动物,采用静水试验法,在水温28.1±0.6℃条件下,开展了氟虫腈、乐果对麦瑞加拉鲮鱼幼鱼的急性毒性研究。结果表明:氟虫腈对麦瑞加拉鲮鱼幼鱼24h、48h、72h、96h的半致死浓度分别为0.020mg/L(95%置信限[0.009,0.066])、0.017mg/L(95%置信限[0.007,0.064])、0.010mg/L(95%置信限[0.004,0.041])、0.004mg/L(95%置信限[0.002,0.017]);乐果对麦瑞加拉鲮鱼幼鱼24h、48h、72h、96h的半致死浓度分别为315.500mg/L(95%置信限[150.453,372.135])、142.233mg/L(95%置信限[64.565,190.985])、62.517mg/L(95%置信限[25.136,102.825])、28.708mg/L(95%置信限[12.759,46.174])。麦瑞加拉鲮鱼幼鱼对氟虫腈、乐果的96h安全质量浓度分别为0.0004mg/L、2.8708mg/L,2种农药的毒性大小为氟虫腈、乐果。最后,还就氟虫腈、乐果对麦瑞加拉鲮鱼幼鱼的急性致毒效应特征以及麦瑞加拉鲮鱼幼鱼对氟虫腈、乐果的安全浓度进行了评价。

活饵料培育大口鲶大规格鱼种的试验

先在池塘中培育麦瑞加拉鲮（简称麦鲮）鱼苗，待规格达到1．3～2cm时，放入规格为5cm的大口鲶鱼种，经过35d培育．大口鲶全长达到12～16．5cm，成活率为86．6％。试验结果表明，利用麦鲮鱼苗作为活饵料，是培育大口鲶鱼种的一种较好的方法。

麦瑞加拉鲮幼鱼对12种原料表观消化率的比较研究

试验以麦瑞加拉鲮(Cirrhinus mrigala)幼鱼(3.88±0.06)g为试验对象,研究其对国产鱼粉、白鱼粉、花生粕、白酒糟、鸡肉粉、米糠、棉粕、菜粕、豆粕、玉米蛋白粉、玉米酒糟和羽毛粉的干物质、粗蛋白、粗脂肪、总能、磷、钙、镁、锌、铜、铁和锰的表观消化率。结果表明:12种试验原料的干物质、粗蛋白质、粗脂肪、总能、磷、钙、镁、锌、铜、铁和锰的表观消化率范围分别为24.93%—85.68%、50.02%—97.40%、51.89%—94.02%、39.18%—96.39%、9.72%—87.37%、3.47%—25.92%、26.11%—88.25%、12.63%—66.35%、41.33%—104.86%、10.69%—91.84%、4.42%—85.49%。其中包括干物质、粗蛋白和总能在内的主要营养物质的表观消化率以国产鱼粉和白鱼粉最高。除鱼粉外的其他原料中,干物质以花生粕、豆粕和玉米蛋白粉最高;粗蛋白以花生粕最高;粗脂肪以米糠和花生粕最高;总能以花生粕和鸡肉粉最高;白酒糟的干物质、粗蛋白、粗脂肪、总能的消化率最低。在矿物质元素表观消化率中,羽毛粉的磷、铜、铁和锰的表观消化率最高;米糠的锌表观消化率最高;钙的表观消化率以白鱼粉、豆粕和羽毛粉最高;镁的表观消化率以豆粕、羽毛粉和玉米酒糟最高;鸡肉粉的磷、钙、镁和铁表观消化率最低;花生粕和棉粕中锌的表观消化率最低;菜粕中铜的表观消化率最低;白酒糟中锰的表观消化率最低。因此,花生粕、豆粕和玉米蛋白粉是麦瑞加拉鲮幼鱼配合饲料中较优质的蛋白源,可进一步开发用于适量替代饲料中的鱼粉;米糠可作为较好的能量饲料;羽毛粉可作为饲料中较好的矿物质元素来源;白酒糟对麦瑞加拉鲮幼鱼而言营养价值最差。

3种常见有机磷农药对麦瑞加拉鲮鱼幼鱼的急性毒性

开展了三唑磷、乙酰甲胺磷、增效水胺硫磷对麦瑞加拉鲮鱼幼鱼的急性毒性试验,结果表明:三唑磷对麦瑞加拉鲮鱼幼鱼24h,48h,72h,96h的半致死浓度分别为0.080mg/L,0.065mg/L,0.060mg/L,0.050mg/L;乙酰甲胺磷对麦瑞加拉鲮鱼幼鱼24h,48h,72h,96h的半致死浓度分别为113.783mg/L,114.451mg/L,113.366mg/L,113.214mg/L;增效水胺硫磷对麦瑞加拉鲮鱼幼鱼24h,48h,72h,96h的半致死浓度分别为0.736mg/L,0.549mg/L,0.469mg/L,0.280mg/L。麦瑞加拉鲮鱼幼鱼对三唑磷、乙酰甲胺磷、增效水胺硫磷96h安全质量浓度分别为0.005mg/L、0.028mg/L和11.321mg/L,3种有机磷农药的毒性大小依次为三唑磷、乙酰甲胺磷、增效水胺硫磷。最后,还就三唑磷、乙酰甲胺磷、增效水胺硫磷对麦瑞加拉鲮鱼幼鱼的急性致毒效应特征以及麦瑞加拉鲮鱼幼鱼对三唑磷、乙酰甲胺磷、增效水胺硫磷的安全浓度进行了评价。

麦鲮和赤眼鳟作为鳜鱼养殖配套饵料鱼适宜性的评价

从生物学的角度比较和评价麦鲮和赤眼鳟作为鳜鱼养殖配套饵料鱼的适宜性,探讨以赤眼鳟代替麦鲮养殖鳜鱼的可行性。结果表明,麦鲮和赤眼鳟食性相近,同属于低龄成熟的多次产卵类型鱼类,对盐度的适应性强,比鳜鱼具有更强的耐低氧能力;一年能进行三次人工繁殖,繁殖力强,易补充亲鱼,繁殖方式和设施与四大家鱼、鳜鱼相似,人工繁殖的效率极高。采用一次放足、分批捕捞的高密度养殖方式,群体产量高,养殖成本低。因此,两种鱼都具有优秀的饵料鱼属性。但在长江流域,赤眼鳟能弥补麦鲮不能自然越冬的缺陷,繁殖期和生长期更长,养殖产量更高,以赤眼鳟代替麦鲮养殖鳜鱼是可行的。这为鳜鱼的养殖,特别是反季节养殖开辟了新的饵料鱼途径,为改进鳜鱼的养殖方式提供了参考依据。

赤眼鳟和麦瑞加拉鲮的化学组成、能量密度及对鳜的营养价值

为评价赤眼鳟(Squaliobarbus curriculus)和麦瑞加拉鲮(Cirrhinus mrigala)对鳜(Siniperca chuatsi)的营养价值,分别测定了体质量为(5.27±1.03)g的赤眼鳟、(5.05±1.21)g的麦瑞加拉鲮和(5.19±0.92)g的鳜的化学组成,估算了这3种鱼的能量密度,以探讨赤眼鳟代替麦瑞加拉鲮养殖鳜的可行性。结果显示,赤眼鳟和麦瑞加拉鲮的全鱼蛋白质含量显著高于鳜,水分显著低于鳜(P<0.05),必需氨基酸指数分别高达92.56%±2.31%和93.17%±0.36%,多数必需氨基酸的化学评分≥0.82。而赤眼鳟的脂肪和能量密度更高,显著高于麦瑞加拉鲮和鳜,灰分显著低于麦瑞加拉鲮(P<0.05)。研究表明,这两种鱼对鳜都具有较高的营养价值,但赤眼鳟的营养价值更高,以赤眼鳟代替麦瑞加拉鲮养殖鳜是可行的,这为转变鳜的养殖方式提供了参考。