罗非鱼网箱健康养殖技术认识罗非鱼1、 罗非鱼最初分布于非洲南部，后来遍布整个非洲大陆的淡水和沿岸的半咸水域。我国最早在1956年从越南引进莫桑比克罗非鱼，在1978年由长江研究所从苏丹引进尼罗罗非鱼，在1994年由上海水产大学引进吉富罗非鱼。目前罗非鱼在我国主养的品种有：奥尼，吉富，吉奥，奥里亚等，另外还有一种红罗非鱼，又叫彩虹鲷，它是尼罗罗非和莫桑比克罗非突变型种之间杂交的后代，经多代选育而形成的一个新品种，子代中有部分黑色的罗非鱼。2、 目前我国每年的罗非鱼产量已经达到100多万吨，占世界总产量的一半以上，成为世界第一大出口国，它也是联合国粮农组织向世界各国推荐的主养品种。罗非鱼具有生长快、养殖周期短、食性广、饵料要求低、病害少、对环境适应性强、苗种容易解决等优点，因此它是良好的养殖对象。罗非鱼因其形状似鲫鱼，所以又叫非洲鲫鱼。罗非鱼有胸鳍、背鳍、臀鳍、尾鳍，尼罗罗非鱼成鱼体侧有与体轴垂直的9条黑带，背鳍下方7条，尾柄上2条。罗非鱼是暖水性鱼类，也属于底层鱼类，但其活动随养殖水体的温度有所变动。它在12—40℃的水中均能生长，其最适宜生长温度为24—32℃。当水中溶氧低于2毫克/升就开始浮头，低于0.28毫克/升就要死亡，所以有“浮的早，浮不死”之说。
罗非鱼雄鱼比雌鱼生长要快40%—50%（如果雌雄同养的池塘中会由于有大量小苗而影响养殖产量和成鱼规格，从而影响最终效益），所以罗非鱼的单雄性养殖就显得尤为重要。体长到6公分（重量50克）以上肉眼就可以分别出雌雄，雌鱼腹部有三个孔，雄鱼有两个孔。罗非鱼繁殖是由雌鱼用嘴含卵孵化。罗非鱼是以植物性饵料为主的杂食性鱼类，是有胃类鱼类，消化能力较强，它有其特殊的消化酶可以消化其他鱼类不易消化的一些藻类，所以罗非鱼养殖除投料外，水质肥一点效果更好。二、网箱的制作与设置利用网箱养殖罗非鱼，可大大提高饲料利用率，降低养殖成本，增加经济效益。网箱结构、规格、设置与常规网箱养鱼基本相同，养殖规模根据实际生产水平，经济实力，市场销售情况确定，网箱的设置要根据罗非鱼的生物学特点进行科学选址和合理布局。1、网箱的制作(1)网箱材料网箱一般由框架、网衣、浮子、沉子四大部分组成，制作网衣的材料有聚乙烯、聚丙烯、尼龙和金属网片。目前制作网衣材料主要是聚乙烯。浮子的材料有楠竹、旧油桶、旧塑料桶，泡沫浮子，和钢筋混凝土浮船。框架材料用楠竹(兼浮子)杉木，钢管等材料制作。沉子有铅粒、石块(砖头)，混凝土倒制等。网箱框架要制作牢固，能抗击风浪和便于日常管理操作，沉子定位要稳固，不能随风浪漂移，定位绳要拉紧并留有余地，便于水位变动时能及时调整升降。
(2)网箱形状网箱形状多样，有长方形、正方形、多边形、圆形等，不管使用何种形状，原则上要求便于管理和增加水体的交换量。云南这边大多数以正方形和长方形为主。(3)网箱规格应根据养殖水域，养殖规模，框架材料等因素来确定。箱体过大，灵活机动性差，分级、防病治病，出箱操作不便，与水体接触交流的面比例小，水体交换差，箱体内的溶氧相对减少。箱体过小，相对投资成本高，饵料容易流失，增加生产成本。实践证明，罗非鱼网箱面积以20～50m2范围较合适，一般采取5×5，7×7规格。(4)网箱网目大小罗非鱼的网箱养殖，必须保证在当年度的养殖周期内要达到商品规格，并出箱销售，尽管在冬季可能实现安全越冬，但生产安排上，尽可能做到不大批量存箱越冬。因此，养殖生产过程中，要求大规格鱼种进箱。生产实践中，罗非鱼进箱最小规格应不低于8cm，相应的网箱网目应在1.8-2.0cm，成鱼网箱可用通用的3cm网目。同时，由于罗非鱼生长速度快，应按生产计划，合理搭配鱼种箱和成鱼箱的比例。(5)网箱的装配网衣的装配一般用穿、绕、并3种方法，纵目使用，箱底四角用砖块或网兜装入大粒卵石重吊，确保网目在水中获得最大的强力度，最大限度提高利用网箱设计容积。
在网箱四周水面上10cm，水面下30cm范围铺设一圈聚乙烯网布，避免饲料流失。2、罗非鱼达到商品规格后，即可出箱销售，但在出箱运输过程中应注意以下事项：①停食3天以上，提前使用海联科应急灵502；②注意天气，避免温差过大，造成鱼应急和大量死亡。五、病害防治人们普遍认为，罗非鱼的抵抗能力强，很少有病害发生，这种概念是不正确的，随着养殖密度增大，养殖环境恶化，罗非鱼的病害一定会发生，并将越来越严重。目前，有几种疾病在养殖过程中已经发生，且发病率高，危害严重，常常造成很大的损失。1、链球菌病①病原：无乳链球菌是养殖罗非鱼的主要病原，可引起罗非鱼的大量死亡。②临床特征不正常行为：由于链球菌可以侵害病鱼的中枢神经系统，故临床表现为病鱼游泳异常，昏沉，常在水面无方向性缓慢游动，有时身体屈曲。眼部损伤：病鱼常呈现眼部症状如眼巩膜白浊，眼球突出以及出血等，但不是所有病鱼都出现眼部症状。干酪样脓肿坏死灶：有时在病鱼的两侧前颊上出现2-3毫米的干酪样坏死灶病变，随后坏死灶破裂形成溃疡，在尾鳍基部可能出现更大(10-20毫米)的坏死灶。坏死灶内是奶酪样的脓质，如果病鱼康复，这种病灶也会长期保留。
皮肤出血：链球菌常引起罗非鱼身体表面出血，表现在口周围，鳍条基部的点状出血，有时在肛门或生殖孔周围呈现出血斑点。腹水：罗非鱼的急性链球菌病常见腹腔内有大量腹水，由于腹水增多，引起肛门突出。③解剖病变胃肠道病变，胆囊明显肿大，有的比正常体积大数倍。败血症，在急性感染时，出现内脏的广泛出血和肝、脾、肾、心、脑、眼和肠道的大面积出血，脾和肾脏肿大。腹膜炎，在严重感染时，病鱼表现严重的腹膜炎症状，所有内脏器官与周围组织粘连，腹腔中有大量纤维性渗出。④诊断方法现场诊断：按照以上阐述的临床症状，对5-10条病鱼进行仔细的现场检查，将内脏器官进行涂片，然后进行革兰氏染色，在显微镜下检查革兰氏阳性球菌将可以确诊该病。实验室诊断：在实验室进行病原菌的分离和细菌学鉴定可以确定链球菌种类。⑤防治减少投喂：当链球菌病爆发时，减少饵料的投喂，可以降低病鱼的死亡率。原因是减少鱼体的进食量可以减少健康鱼的感染机会。降低饲养密度：当疾病发生，刚出现死亡时，应该降低饲养密度减少应激因素和疾病传播机会，有助于降低鱼群的死亡、减少损失。抗生素冶疗：抗生素（氟苯尼考）只有在莲球菌暴发的早期应用才能有效，因为受感染的鱼几乎不会吃料，达不到治疗效果，只有那些未被感染，还能正常吃食的鱼，才能起到预防作用。
免疫防治：目前尚无高效的商品疫苗能预防罗非鱼链球菌病的爆发，但是，不久的将来，疫苗防治将成为预防罗非鱼链球菌病的主要手段。2、小瓜虫小瓜虫病：病原体是小瓜虫的幼体或成虫，发病鱼体体表有白点，口内也有白点，病鱼不吃食，可大面积流行和爆发。目前没有特效药，可采用15ppm-25ppm的福尔马林浸洗，每天1次，2-3次为一个疗程；或者采用辣椒面和干姜片，混合煮沸，兑水泼洒。在诊断的时候容易和孢子虫病发生误诊，所以最好做镜检，如果没有显微镜，可以采取以下方法鉴别:取白点放在玻璃上，成三角形，等几分钟，如果形状发生变化的就是小瓜虫，不变的就是孢子虫。以上讲的是罗非鱼养殖当中最难治疗的两种疾病，前一种是细菌病，后一种是寄生虫病，其实罗非鱼养殖过程中遇到的病害还有很多，这里不再全部罗列出来，但是只要我们平时加强水质管理，加强鱼体自身体质，定期配合海联科拌料内服105+505，提高鱼体抗病力，就会减少疾病的发生，降低养殖风险，获得更好的养殖效益。real, in each pen business lending Qian not for by pen query, led to mortgage failure of. (Vi) not in accordance with the relevant provisions of the Bank operation, failed to identify false documents, certificates, authorizations, warrants, etc. (VII) in the credit risk management system to provide false information, is not required by the guest rating credit management objective, impartial ratings of credit, resulting in credit decision-making errors.(H) the investigation report conclusions of false record, misleading statement or material omission, resulting in credit decision-making errors. (I) the orders, directives, orders, suggest that others not involved in the investigation business, issued by the investigators. (10) without the approval of authorities, after the first credit investigation, credit first and then record, counter-current process operations such as operation prior to approval. (11) article does not meet the risk management Department, Marketing Management Department to carry out supervision and inspection and due diligence evaluations or providing false information. (12) other violations result in credit business at substantial risk or significant potential risk behaviours. Sixth chapter supplementary articles article 28th of this approach by the Head Office of risk management Department is responsible for the interpretation and amendment. 29th spontaneous herein from the date of implementation. Qilu silver computer transmission of qilu Bank documents (2012), No. 289Qilu Bank personal credit on issuing the Notification Guide to business risk management branch, jurisdiction and the jurisdiction of business lines, Jinan branch, head office departments within its jurisdiction: in order to improve the quality of individual credit business, optimize the structure of assets, promotion of real, in each pen business lending Qian not for by pen query, led to mortgage failure of. (Vi) not in accordance with the relevant provisions of the Bank operation, failed to identify false documents, certificates, authorizations, warrants, etc. (VII) in the credit risk management system to provide false information, is not required by the guest rating credit management objective, impartial ratings of credit, resulting in credit decision-making errors.(H) the investigation report conclusions of false record, misleading statement or material omission, resulting in credit decision-making errors. (I) the orders, directives, orders, suggest that others not involved in the investigation business, issued by the investigators. (10) without the approval of authorities, after the first credit investigation, credit first and then record, counter-current process operations such as operation prior to approval. (11) article does not meet the risk management Department, Marketing Management Department to carry out supervision and inspection and due diligence evaluations or providing false information. (12) other violations result in credit business at substantial risk or significant potential risk behaviours. Sixth chapter supplementary articles article 28th of this approach by the Head Office of risk management Department is responsible for the interpretation and amendment. 29th spontaneous herein from the date of implementation. Qilu silver computer transmission of qilu Bank documents (2012), No. 289Qilu Bank personal credit on issuing the Notification Guide to business risk management branch, jurisdiction and the jurisdiction of business lines, Jinan branch, head office departments within its jurisdiction: in order to improve the quality of individual credit business, optimize the structure of assets, promotion ofreal, in each pen business lending Qian not for by pen query, led to mortgage failure of. (Vi) not in accordance with the relevant provisions of the Bank operation, failed to identify false documents, certificates, authorizations, warrants, etc. (VII) in the credit risk management system to provide false information, is not required by the guest rating credit management objective, impartial ratings of credit, resulting in credit decision-making errors.(H) the investigation report conclusions of false record, misleading statement or material omission, resulting in credit decision-making errors. (I) the orders, directives, orders, suggest that others not involved in the investigation business, issued by the investigators. (10) without the approval of authorities, after the first credit investigation, credit first and then record, counter-current process operations such as operation prior to approval. (11) article does not meet the risk management Department, Marketing Management Department to carry out supervision and inspection and due diligence evaluations or providing false information. (12) other violations result in credit business at substantial risk or significant potential risk behaviours. Sixth chapter supplementary articles article 28th of this approach by the Head Office of risk management Department is responsible for the interpretation and amendment. 29th spontaneous herein from the date of implementation. Qilu silver computer transmission of qilu Bank documents (2012), No. 289Qilu Bank personal credit on issuing the Notification Guide to business risk management branch, jurisdiction and the jurisdiction of business lines, Jinan branch, head office departments within its jurisdiction: in order to improve the quality of individual credit business, optimize the structure of assets, promotion of
