Effectiveness of four methods for tagging juveniles of farm-reared gilthead sea bream, Sparus aurata, L.

This study tested different tags for each size of farm-reared gilthead sea bream, Sparus aurata L. juveniles, used in enhancement programmes. The following tags were tested: dye mark, fingerling tag, opercular tag, anchor tag A (filament diameter of 1.20 mm) and anchor tag B (0.85 mm). Tag/mark retention, wounds produced by the tag, ease of application, ease of detection and cost were examined. Epidermal dye marks had poor retention and detection rates. Of the tags tested, retention was greater for the anchor tag A (80–100%) after 7 months; anchor tag B showed a retention rate of only 20% after 3 months. The fingerling tag had a retention rate of 27.5% after 12 months. The opercular tag had a retention rate of 44% after 20 days but fractured the opercular bone in many cases. Tag incisions and wounds persisted in some fish for the duration of the experiment.     

Dietary threonine requirement of fingerling Indian major carp,Labeo rohita (Hamilton)

An 8‐week feeding experiment was conducted in a water flow‐through system (26–28 °C) to determine the dietary threonine requirement of fingerling Labeo rohita (3.90±0.03 cm; 0.58±0.02 g). Growth, feed utilization and body composition of fish fed test diets (40% crude protein; 17.9 kJ g^?1 gross energy) with graded levels of l ‐threonine (0.75%, 1.0%, 1.25%, 1.50%, 1.75% and 2.0% dry diet) to apparent satiation were response variables used to assess threonine adequacy. Diets were made isonitrogenous and isoenergetic by adjusting the levels of glycine and dextrin. The amino acid profiles of the test diets were formulated to that of 40% whole chicken egg protein except for threonine. The performance of fish fed experimental diets was evaluated using calculated values for weight gain (g fish^?1), feed conversion ratio (FCR), protein efficiency ratio (PER) and protein productive value (PPV) data. Maximum weight gain (g fish^?1) (1.79), lowest FCR (1.39), highest PER (1.76) and PPV (0.33) were recorded at 1.50 g per 100 g dietary threonine. Statistical analysis of weight gain, FCR, PER and PPV data reflected significant differences (P<0.05) among treatments. Except for reduced growth performance in fish fed threonine‐deficient diets, no deficiency signs were noted. Weight gain, FCR, PER and PPV data were also analysed using second‐degree polynomial regression analysis to obtain a more accurate threonine requirement estimate, which was found, using each response variable, to be at 1.70, 1.63, 1.65 and 1.51 g per 100 g of dry diet, corresponding to 4.2, 4.07, 4.12 and 3.77 g per 100 g of dietary protein respectively. Based on the second‐degree polynomial regression analysis of the live weight gain, FCR, PER and PPV data, the optimum dietary level of threonine for fingerling L. rohita was found to be in the range of 1.51–1.70 g per 100 g of the dry diet, corresponding to 3.77–4.2 g per 100 g of dietary protein.     

乌鳢苗种繁育及池塘高产养殖技术

为探讨乌鳢的人工养殖技术,对乌鳢苗种繁育及池塘养殖阶段的关键环节:亲鱼培育、人工催产、鱼卵孵化、鱼种培育、成鱼养殖等进行了系统研究。并总结了一套实用的乌鳢养殖技术。实践证明,使用该技术能提高乌鳢鱼苗成活率和成鱼产量。     

三角鲤人工繁殖研究

使用广西水产研究所池塘人工驯化饲育3年的天然三角鲤亲鱼1676尾,采用经筛选的鱼类敏感药物(PG、LHRH-A2、HCG)单一或混合催产的方法,在2002-2005年,先后进行了10批共600组的三角鲤人工繁殖试验。收集受精卵795.5万粒,在水温20.0~28.5℃条件下,利用环道池孵化出鱼苗680.9万尾,平均孵化率为85.6%。并使用光学显微镜观察了自受精卵至鱼苗破膜而出的发育全过程,拍摄了各个阶段胚胎发育图谱。培育出2.5 cm以上鱼种631.7万尾,平均成活率达92.8%。     

草鱼种与泥鳅池塘双主养模式养殖试验

[目的]降低草鱼池塘养殖生产成本,提高池塘水体利用率和综合养殖效益,增强养殖模式的抗风险能力以及示范推广作用.[方法]在江苏省宿迁市宿城区中扬镇开展了草苗种、泥鳅池塘双主养模式养殖试验.[结果]放养260尾/kg的泥鳅苗种180 000尾/hm2,放养2 000尾/kg的草苗种60 000尾/hm2的养殖模式,以及放养260尾/kg的泥鳅苗种120 000尾/hm2,放养2 000尾/kg的草苗种75 000尾/hm2的养殖模式,产出投入比均较高.[结论]放养260尾/kg的泥鳅苗种120 000尾/hm2,放养2 000尾/kg的草苗种75 000尾/hm2的养殖模式更容易被养殖者接受,更容易被大面积推广应用.     

罗非鱼鱼种肠炎病的病理组织学及病原体的研究

本文从病理组织学的角度,研究了罗非鱼鱼种肠炎病的发生与发展,为其诊断与防治奠定了理论基础。结果表明,该病病原体为产气单胞菌。     

杂交鲶(怀头鲶♀×鲶♂)人工繁殖与苗种培育技术

采用捕自黑龙江水域的怀头鲶为母本，鲶鱼为父本，应用自制催产药物DOS与LRH-A2、HCG进行人工催产，使催产率、受精率分别达到92％和88％。20-21．5℃水温条件下43h孵化出苗，孵化率75％。出膜仔鱼体长3．93mm，7．83mm下塘，池塘培育8天达到34．08mm，培育成活率50％。     

黄颡鱼的生物学特性与养殖技术

通过对黄颡鱼的生物学特性、繁殖技术、苗种培育技术、养殖技术、放养模式、病害防治技术的系统研究，探明了黄颡鱼的食性、溶氧需求、温度适应性、盐度耐受性等生物学特性，报道了黄颡鱼繁殖与苗种培育措施，提出池塘养殖所需配套技术及常见病害防治技术。     

Effect of sub-lethal nitrite on selected haematological parameters in fingerling Catla catla (Hamilton)

A sub‐lethal nitrite toxicity trial was conducted using static conditions for a period of 96 h with fingerlings of Catla catla (21.4±3.6 g). Fingerlings were exposed to five concentrations of nitrite, that is, 1, 2, 4, 8 and 10.4 mg L^?1 and a nitrite‐free control to study changes in haematological parameters. Nitrite caused an increase in immature erythrocyte population (7–24%) in lower concentrations (0–4 mg L^?1) at 6 h while they were absent in higher concentrations. The total erythrocyte count was reduced at 6 h followed by an increase at 12 h with further reduction up to 96 h in all concentrations of nitrite. The 96‐h exposure resulted in 21.2–31.8% reduction in erythrocyte population in 1–10.4 mg L^?1 nitrite. The haemoglobin content decreased progressively with increasing nitrite concentrations as well as exposure periods. Total leukocyte count decreased initially at 6 h in all treatments followed by an increase after 12 h, signifying development of a protective response of the body to nitrite stress. Blood glucose decreased initially up to 24 h followed by an increase through 96 h. Serum protein level decreased continuously with increasing exposure period. The study revealed that exposure to nitrite caused changes in almost all the haematological parameters in the fingerlings depending on the concentration as well as exposure period. Nitrite being one of the important inorganic nutrients often recorded at higher levels in intensively cultured ponds, the present study highlights its adverse impact on fish and stressed the need for the management of this nutrient in culture ponds.     

Effect of dietary supplementation with taurine, β-alanine andGABA on the growth of juvenile and fingerling Japanese flounder Paralichthysolivaceus

ABSTRACT:   Three diets supplemented with taurine, β-alanine andGABA and a control diet were fed to juvenile and fingerling Japaneseflounder to investigate the effects of the diets on growth and metabolicchanges of free amino acids in whole body and tissues. In experimentI, three diets supplemented with 1% each of taurine, β-alanineand GABA and a control diet were fed to juvenile Japanese flounderwith an initial mean body weight of 0.4 g for 4 weeks at20°C. In experiment II, the taurine-supplemented diet anda control diet were fed to fingerling Japanese flounder with an initialmean body weight of 15 g for 4 weeks at 20°C.Only supplementation of taurine in the diet of juvenile flounderimproved their growth performance in experiment I, but fingerlinggrowth performance of experiment II was not significantly relatedto taurine supplementation in the experimental diet. These resultssuggest that there is a greater requirement for taurine for thegrowth of juvenile Japanese flounder than fingerling Japanese flounder.