成鳗池的水质培育

成鳗养殖过程中，在强化选种与投饲的同时，培育好水质是养殖成败的关键。培育水质主要是设法控制池中氧气的生产和消耗过程，防止水质突变而造成缺氧。其方法是培养浮游植物主要是微囊藻，通过其光合作用产生大量氧气。另外可用增氧机来调整溶氧。微囊藻所以能大量繁殖与水中含有丰富的有机质有关。在我国家鱼养殖中，一般认为微囊藻大量繁殖是有害的，但在养鳗中则可以认为是有利的，因为它大量繁殖能增加水中溶氧，水质比较稳定，且鳗鲡能利用微囊藻作为体内维生素Ａ的来源。同时微囊藻大量繁殖使水质变浓，透明度降低，池底层光线变…     

水净化机和人造水藻在循环水养鳗设施中的应用

当今,节约热能、电能和水资源等在工农业上已提到议事日程上,而在水产养殖上谈论节能问题还显得十分生疏,但在温流水养鳗业中,能源和水资源的消耗却是个举足轻重的大问题。常规养鳗设施,大多为仿日本注水式鳗池,池形为八角形,使用水车式增氧机增氧,为保证水质,每天换水量约为总水量的30％—40％,水源一般采用水温为18—19℃的深井水,而养殖鳗鱼最佳水温为27—29℃,除夏天外一般均需用蒸汽升温。一个面积为一万m~2的中型温流水养鳗场,每天换水量约为2000-2500m~3,如能将池水就地加以净化,然后返回原池重复使用,将日补充水量降低在5％-8％之间,一则可节约水资源80％左右,二则可大大节省增温热能。为此我们将水净化机和人造水藻在养鳗池中加以应用,利用其生物膜对水体不断净化,并以风机增氧代替水车式增氧机增氧,降低热能在空气中的散失从而达到上述之目的。目前,用水净化机和人造水藻对工业和生活污水加以净化的水处理技术已日臻完善,今将此技术应用于养鳗业,和养鳗技术有机地融为一体,实是循环水养鳗水质净化的一种新的途径。吴江市养鳗场是国内唯一自行设计并将此工艺应用于生产的养鳗场。该场成鳗养殖池面积为2400m~2,鳗种池面积为1383m~2。通过三年来设备调试与生产实践,1991年向外贸交售成鳗50吨,内销成鳗10吨。全年共生产成鳗60吨,平均每平方米成鳗池生产成鳗25公斤,折16.67吨/亩。1992年1～6月已产成鳗50吨,达国产养鳗设施的先进水平。     

微孔增氧技术操作规程

“微孔增氧”技术就是池塘管道微孔增氧技术,也称纳米管增氧技术。“微孔增氧”采用底部充气增氧办法,增氧区域范围广,溶氧分布均匀,增加了底部溶氧,加快对底部氨氮、亚硝酸盐、硫化氢的氧化,抑制底部有害微生物的生长,“微孔增氧”造成水流的旋转和上下流动,将底部有害气体带出水面,改善了池塘的水质条件,减少了病害的发生。池水溶氧的充足,保证了池塘水质的相对稳定,提高了饲料利用率,促进了鱼类的生长,提高了水产养殖的成活率、规格和产量。“微孔增氧”还具有节能、低噪、安全等优点,在主机功率相同的情况下,微孔增氧机增氧能力是叶轮式增氧机的3倍。     

鳗苗捕捞技术

鳗鲡又名河鳗,是优良的养殖鱼类。养鳗业收益大,在日本和我国台湾省较发达,被誉为“淘金业”。我国养鳗正在发展中,但是河鳗的人工繁殖尚未解决,鳗苗至今还得靠捕捞天然苗。捕捞天然鳗苗除解决养鳗需要外,还可以出口换外汇,有“一两鳗苗一两黄金”之称。为了提高鳗苗捕捞产     

渔业纵览

邵武市向养鳗业主发出健康养殖倡议书为全面治理整顿和彻底解决鳗鱼养殖中“孔雀石绿”等禁用药品和化合物残留问题,近日,邵武市畜牧水产局向全市各养鳗业主、渔药、饲料等经营单位发出倡议。一是各养鳗业主应自觉遵守国家法律法规,坚决不使用“孔雀石绿”等违禁兽药和化合物。     

颗粒型增氧剂“粒粒氧”与粉状增氧剂

通过将颗粒型的增氧剂“粒粒氧”和普通粉状的增氧剂在池塘水体中进行增氧效果试验,以了解同一性质的两种不同剂型的增氧剂对水体增氧效果的差异。试验结果显示,在增氧剂加入池塘后,普通粉状的增氧剂仅对水体表层有增氧效果,且在试验后20分钟达到最大值,对底层养殖水体几乎没有增氧效果;颗粒型增氧剂“粒粒氧”对水面的增氧效果与粉状的增氧剂接近,并能维持4小时之久。这表明颗粒型增氧剂“粒粒氧”具有缓释的功能,其     

网箱养鳗 大有可为

鳗鱼营养丰富,滋味鲜美,享誉“水中人参”,成鳗一直是销路很好的出口创汇产品,近年来,我国东南沿海各省市都大力发展养鳗生产,限于池塘或流水养鳗投资大,成本高,许多地区和单位因资金无法解决,明知有利可图,只得望“鳗”兴叹。但网箱养鳗非常适宜各地推广,为养鳗业的发展和普及开辟了新的途径。首先,网箱养鳗比目前普遍采用的池塘或流水养鳗成本大幅度降低。一是投资省,不占用农田,不需要鳗池和水电配套建设,池塘养鳗每亩鳗池仅     

苏北地区养鳗业的调整思路

苏北地区养鳗业的调整思路养鳗业具有成本高、投资大、风险大等特点。苏北的养鳗场多数是在１９８５年前后“一哄而起”发展的，后来经过几年来的调整，一些经济实力较差的养鳗场经不起市场的冲击而被迫倒闭，生存下来的养鳗场目前的经营效益并不理想。要提高养鳗的经营效...     

苏北地区养鳗业调整思路

养鳗业是在高价位轨道上运行的行业,具有成本高、投资大、风险大等特点。苏北的养鳗场多数是在1985年前后“一哄而起”发展的,后来经过几年来的调整,一些经济实力较差的养鳗场经不起市场的冲击而被迫倒闭,生存下来的养鳗场目前的经营效益并不理想。要提高养鳗的经营效益,必须根据苏北地区的条件和基础对现有的养鳗模式进行适当调整,根据最近向苏北地区一些养鳗场和多年从事养鳗行家的调查了解,他们提出以下三个方面的调整思路:     

压力式氧溶解装置在凡纳滨对虾养殖方面的应用

研究设试验组和对照组,试验组使用压力式氧溶解装置进行池塘增氧和自动化在线溶氧监测,对照组为常规充气式增氧机。试验证实,试验组能够保证养殖期间凡纳滨对虾对水体溶氧水平(4mg/L)的需求,而对照组则不能完全满足对虾养殖对溶氧的要求。试验组虾的生长情况要明显好于对照组;试验组池塘的水色始终保持茶褐色,而对照组为绿色,并伴有微囊藻水华。     

养鳗池塘生态系统中矿物元素及其影响因素

对比分析了6口处于不同养殖阶段的日本鳗鲡(Anguill japonica)池塘水体、水源、底泥及饲料中的矿物元素,探讨了池塘生态系统中矿物元素的主要影响因素和生产管理对策,结果表明:1)养鳗池塘水体矿物元素与所处养殖阶段投入饲料的品种相关,底泥中矿物元素部分在养殖过程中积累而来;2)主成分分析结果表明钙、镁、铝元素是...     

高产成鱼池蓝绿色裸甲藻水华的研究

由蓝绿色裸甲藻(Gymnodinium,sp．)形成的蓝绿色水华是无锡渔区高产鱼池典型水质之一。本文对该藻的形态特征、生态、池塘培育和控制以及对鱼类的影响进行了研究。蓝绿裸甲藻水华具喜温、喜光、喜有机氮肥,喜红褐色水色(生物因子),且对外界环境的变化十分敏感等生态特点。蓝绿裸甲藻水华池的理化条件较差,特别是藻体繁殖过度,极易恶化水质,造成鱼类泛池。采用增施有机氮肥、合理使用增氧机、加水等综合措施可促进和控制该藻的繁殖。经鱼类消化道镜检表明,蓝绿裸甲藻能被鲢、鳙鱼及鲤、鲫、罗非鱼鱼种大量摄食,并被鱼类消化。对无锡河埒渔业一队成鱼池三年统计,蓝绿裸甲藻水华池的鲢鳙鱼净产量比无水华池高33．4～37．5％。     

Combined production of fish and plants in recirculating water

A pilot plant of ca 2000 l of recirculating fresh water for intensive fish production was constructed in a controlled-environment greenhouse. The feasibility was examined of using nutrients from fish waste-water, mainly oxidized nitrogenous compounds, for plant production, combined with an activated sludge system for water purification.The reduction of nitrates, formed during the extended aeration process by nitrifying bacteria, was not sufficient by higher plants and unicellular algae alone to reduce the nitrate concentration in our system significantly. An additional microbial denitrification step had to be included to effect maximal decrease in nitrogenous compounds.For fish culture in the pilot plant Tilapia mossambica and Cyprinus carpio were chosen as experimental fishes. Both fish species showed significant weight increases during the course of the experiment.Ice-lettuce and tomatoes were tested both in recirculating water and in batch culture. The unicellular algae Scenedesmus spp. were grown in a non-sterile batch culture. All plants grew well in the waste-water without additional nutrients.Determination of the physical and chemical parameters for optimum water purification, the most suitable ratio of denitrification by plants and by microorganisms, and the most favourable fish and plant species for combined culture in recirculating water are important and of current interest in view of the increasing demand for clean, fresh water, and the pressing need to find new ways of producing protein for human nutrition under prevailing conditions of an exponentially expanding world population.     

欧鳗山区溪流养殖试验——幼鳗,成鳗的养殖

本文总结了１９９５－１９９６年来龙岩山区欧鳗的养殖结果，平均体重每尾２．４克幼鳗经三个月的养殖，成活率达８０％，饲料系数０．７５以上，成鳗养殖成活率可达９５％以上，饲料系数平均０．５４。结果表明：控制欧鳗养殖水日交换量大于１００－１５０％，建立蓄水池，进行水处理，解决雨季鳗场用水，采用优质配合饲料，定期进行病虫害防治，特别是拟指环虫病的防治，是山区欧鳗养殖成功的关键。     

黄鳝体内睾酮、雌二醇和炔诺酮含量的检测分析

检测并分析了黄鳝体内睾酮、雌二醇和炔诺酮的含量。结果显示，野生和人工饲养的黄鳝，其血清中睾酮、雌二醇的平均值为0．055ng／ml和22．43pg/ml，野生黄鳝中睾酮、雌二醇的含量普遍高于人工饲养的黄鳝，Student′↑s t检验差异显著。在野生及人工饲养的黄鳝体内均未检出炔诺酮。饲养试验的结果表明，如果黄鳝摄食了添加一定浓度炔诺酮的饲料，能检出其体内炔诺酮的残留。     

山东淡水渔业良种生产现状与对策

分析了山东省主要淡水鱼优良性状退化原因,提出科学繁育、混合选择、开发引进国内外优良品种等对策。建议开发养殖鳜、乌鳢、黄蟮、青虾、中华鲟、胭脂鱼等,引进匙吻鲟、大口胭脂鱼等,并加快良种产业化开发。     

Geosmin depuration from European eel (Anguilla anguilla) is not affected by the water renewal rate of depuration tanks

This study established that geosmin depuration from European eel is not affected by the water renewal rate of depuration tanks. A general fish bioaccumulation model extended with terms that account for effects of tank water renewal rate and system losses of chemicals, predicted strong effects of the water renewal rate of depuration tanks on geosmin depuration from European eel. Model predictions were validated in a depuration experiment with geosmin‐loaded European eel (n = 95) with a mean (SD) individual weight of 134.4 (5.0) g and a mean (SD) lipid content of 33.7 (2.8) % (w/w). Fish were depurated for 24, 48 or 72 h at three different tank water renewal rates (0.3, 3.3 and 33 day^?1). Treatments were installed by three different mean (SD) water flow rates (13.8 (1.3), 143.5 (9.2) and 1511 (80) L kg fish^?1 day^?1) over 30‐L tanks. Eels eliminated geosmin from their bodies, but unlike the model predicted, this was independent of the water renewal rate of the depuration tanks. Although being eliminated from the fish, geosmin hardly appeared and certainly did not accumulate in the water of the depuration tanks as the model predicted. This observation may be explained by geosmin being eliminated from eel as metabolite rather than the parent compound. Geosmin elimination from eel seems not to occur according to the generally accepted passive diffusion mechanism for excretion of lipophilic chemicals, and geosmin biotransformation by the eel seems indicated. Clearly geosmin depuration from European eel cannot be enhanced by increasing water renewal rates of depuration tanks.     

Management of a closed brackish water system for high-density fish culture by biological and chemical water treatment

During a 1-year operation of a warm water recycling system (salinity about 8‰) sufficient water quality was maintained under high stocking density conditions using Tilapia and the European eel as potential candidates for intensive farming. The final fish: water ratio was 1 : 23 (or 43.5 g fish per 1 water) for the whole experimental culture unit. The total water volume of the system was about 5 m³. The water treatment unit held 52% of the total volume, whereby 46% was available for fish culture. Combined biological (trickling filter with Hydropack-foil) and chemical (ozonation) water treatment proved to be useful to meet water quality requirements under these rearing conditions. After an initial conditioning period of the biofilter, BOD varied from 4.5 to 6.0 mg O₂/l, ammonium levels were maintained at less than 1 mg/l and nitrite concentrations averaged 1 mg/l. The average efficiency (oxidation rate) of the biofilter for NH₄⁺-and NO₂^?-oxidation was 31% and 13.2%, respectively. The pH was stabilized slightly above 7.0 when a denitrification unit was connected to the system. Nitrate concentration of the system levelled of between 200 and 400 mg/l and was regulated by the addition of an electron donator (first glucose solution, then methanol) to the denitrification unit; the elimination rate averaged 50% with a maximum of 98%. High nitrite levels were avoided by ozone treatment of the recycled water. The accumulation of low-biodegradable substances was also successfully counteracted by ozonation. Fish growth rates of about 30% per month at high stocking densiteis were reached for Tilapia at a fish: water ratio of 1 : 4.6 (217 g fish per 1 water), indicating that a combination of biological water treatment and ozonation supports intensive fish culture in a closed aquaculture system.     

Somatic growth, survival, feed utilization and starvation in European elver Anguilla anguilla (Linnaeus) under two different photoperiods

The aim of the study was to determine the effect of two photoperiod regimes under artificial conditions on growth performance and survival in the European eel Anguilla anguilla during the transition from glass eel to elver. The fish were held in 12-h-light:12-h-dark (12L:12D) and in continuous darkness (DD) in fed and fast trials lasting 80 days. Fed fish kept in the dark showed higher somatic growth, and a better feed conversion ratio, higher protein and lipid content, with significant differences between treatments. Dark environment increased the survival rate in comparison with fish exposed to 12L:12D, during which eels showed lower survival rates and greater variations in size. Fasted fish suffered loss of body mass in both photoperiods at the end of the experimental phase, but fish exposed to 12L:12D lost more body mass. These results indicate that the photoperiod is a key factor during the glass eel–elver stage, which may contribute to optimizing the early stages of eel culture.     

A technique for maintaining water quality in fish tanks containing eels and fish larvae

Abstract. A technique which uses electrodes at the mouths of meshless water outlets of fish tanks is described. The electrical field generated by the electrodes was effective in discouraging fish from approaching the open outlet, and allowed free discharge of debris-laden water without the usual blockage of the outlets by faeces and uneaten food. The system was found to be particularly effective for the rearing of eels (from the glass eel stage on) which typically cause a rapid deterioration in water quality due to their feeding behaviour. It was also found very useful for rearing other fish larvae in tanks.