（原创）接着上，鱼类疾病（健康）第二讲
<div id="textstyle_5462" style="PADDING-RIGHT: 0px; MARGIN-TOP: 10px; FONT-SIZE: 9pt; OVERFLOW-X: hidden; WIDTH: 97%; WORD-BREAK: break-all; TEXT-INDENT: 24px; LINE-HEIGHT: normal; HEIGHT: 200px; WORD-WRAP: break-word;"><p><span>鱼类疾病</span><span><font face="Times New Roman"><br/> </font></span><span>第二讲</span><span lang="EN-US"><font face="Times New Roman"><span> </span>Fish health<span> </span>July 13, 2007</font></span></p><p><span lang="EN-US"><span><font face="Times New Roman"> </font></span></span><span>前一讲谈到</span><span lang="EN-US"><font face="Times New Roman">90%</font></span><span>的鱼类疾病都是由水质的恶化所导致的，因此水质的监控在鱼类养殖过程中就处于至关重要的位置。然而水质的大部分参数都是不可见的，唯一的可见参数只有水中固体颗粒的溶度。本节我们来谈谈固体颗粒溶度对鱼类健康的影响。</span><span lang="EN-US"><span><font face="Times New Roman"> </font></span></span></p><p><span lang="EN-US"><span><font face="Times New Roman"> </font></span></span><span>固体颗粒按成分来区分共有</span><span lang="EN-US"><font face="Times New Roman">2</font></span><span>种。第一种是无机颗粒，就是我们常说的淤泥。第二种是来自排泄物，未吃完的食物及石头碎屑的有机颗粒。这些颗粒在对鱼类健康方面产生的危害主要表现在下面</span><span lang="EN-US"><font face="Times New Roman">5</font></span><span>点：</span></p><p><span lang="EN-US"><font face="Times New Roman">1．<span><br/> </span></font></span><span>鳃：过多的颗粒会影响正常的鳃对气体进行交换及在鳃上的细菌附着。</span></p><p><span lang="EN-US"><font face="Times New Roman">2．<span><br/> </span></font></span><span>微生物生长：过多的颗粒会促进水中微生物的生长，有害微生物将对鱼产生危害。</span></p><p><span lang="EN-US"><font face="Times New Roman">3．<span><br/> </span></font></span><span>较高的</span><span lang="EN-US"><font face="Times New Roman">BOD</font></span><span>（生物氧气需求）：颗粒所促进生长的微生物将会消耗过多的氧气，导致鱼类的供氧不足。</span></p><p><span lang="EN-US"><font face="Times New Roman">4．<span><br/> </span></font></span><span>抑制光合作用：过多的固体颗粒会降低水中植物可利用的光照从而一直光合作用。</span></p><p><span lang="EN-US"><font face="Times New Roman">5．<span><br/> </span></font></span><span>其他污染物：固体颗粒中可能携带许多污染性物质。</span></p><p><span lang="EN-US"><span><font face="Times New Roman"> </font></span></span><span>固体颗粒按形态可分为</span><span lang="EN-US"><font face="Times New Roman">2</font></span><span>种。其一是沉底性颗粒，其二是悬浮性颗粒。沉底性颗粒本身的重量，体积都比悬浮性颗粒来得大，因此前者相对比较容易从水体中清除，而后者因体积小较难清除。对在野外生活的鱼类而言，沉底性颗粒的危害主要表现在对鱼卵的覆盖窒息。科学测试表明，正常情况下野生鲑鱼卵的成活率大于</span><span lang="EN-US"><font face="Times New Roman">85%</font></span><span>，然而在有沉积底物的环境下成活率小于</span><span lang="EN-US"><font face="Times New Roman">30%</font></span><span>。另外，沉底性颗粒对鱼类的危害还表现在以下</span><span lang="EN-US"><font face="Times New Roman">3</font></span><span>点：</span></p><p><span lang="EN-US"><font face="Times New Roman">1．<span> </span></font></span><span>增加水中微生物的含量，微生物作为一种</span><span lang="EN-US"><font face="Times New Roman">N</font></span><span>源将对鱼产生负面影响。</span></p><p><span lang="EN-US"><font face="Times New Roman">2．<span> </span></font></span><span>腐化作用：沉底性颗粒被腐化后将产生具有毒性的</span><span lang="EN-US"><font face="Times New Roman">NH<sub>3</sub></font></span><span>和</span><span lang="EN-US"><font face="Times New Roman">H<sub>2</sub>S</font></span><span>。</span></p><p><span lang="EN-US"><font face="Times New Roman">3．<span> </span></font></span><span>沉底性颗粒将消耗氧气，增加</span><span lang="EN-US"><font face="Times New Roman">BOD</font></span><span>。</span></p><p><span lang="EN-US"><span><font face="Times New Roman"> </font></span></span><span>悬浮性颗粒对鱼类健康产生的危害表现在下面几点：</span></p><p><span lang="EN-US"><font face="Times New Roman">1．<span> </span></font></span><span>影响鱼的捕食视线</span></p><p><span lang="EN-US"><font face="Times New Roman">2．<span> </span></font></span><span>影响操作管理人员对鱼进行日常观察</span></p><p><span lang="EN-US"><font face="Times New Roman">3．<span> </span></font></span><span>对鱼鳃会起到磨蚀作用</span></p><p><span lang="EN-US"><font face="Times New Roman">4．<span> </span></font></span><span>成为细菌生长的基质</span></p><p><span lang="EN-US"><span><font face="Times New Roman"> </font></span></span><span>水产养殖上对固体颗粒溶度的测量使用</span><span lang="EN-US"><font face="Times New Roman">NTU</font></span><span>为单位，测量仪器有</span><span lang="EN-US"><font face="Times New Roman">SECCHI</font></span><span>盘和探测感应头一起（十分昂贵，</span><span lang="EN-US"><font face="Times New Roman">$3000</font></span><span>）。水中固体颗粒溶度小于</span><span lang="EN-US"><font face="Times New Roman">5NTU</font></span><span>（</span><span lang="EN-US"><font face="Times New Roman">20mg/L</font></span><span>）为正常值。大于</span><span lang="EN-US"><font face="Times New Roman">25NTU</font></span><span>（</span><span lang="EN-US"><font face="Times New Roman">100mg/L</font></span><span>）时水质已经恶化得十分严重。移除固体颗粒在水产养殖上使用鼓式过滤器和沙滤，其中沙滤效果比较好，但需要定期清理。观赏鱼养殖用沙滤比较合适。对机械过滤而言（鼓式过滤器）大于</span><span lang="EN-US"><font face="Times New Roman">50</font></span><span>微米的颗粒是比较容易移除的，小于</span><span lang="EN-US"><font face="Times New Roman">20</font></span><span>微米就相对难移除。</span></p><p><span>另外一种过滤颗粒方式是采用化学试剂，比如凝聚剂，成分大多是铝盐，过滤原理是让小颗粒容易凝聚成大颗粒，增加过滤的容易度。</span></p><p><span lang="EN-US"><span><font face="Times New Roman"> </font></span></span><span>在日常水产养殖上对于固体颗粒的处理要做到以下几点：</span></p><p><span lang="EN-US"><font face="Times New Roman">1．<span><br/> </span></font></span><span>在颗粒凝集变大前移除颗粒。</span></p><p><span lang="EN-US"><font face="Times New Roman">2．<span><br/> </span></font></span><span>使用具有自我清理功能的养殖容器，比如圆形玻璃纤维桶。</span></p><p><span lang="EN-US"><font face="Times New Roman">3．<span><br/> </span></font></span><span>排水要做到在容器中心利用水流对颗粒进行有效移除。</span></p><p><span lang="EN-US"><font face="Times New Roman">4．<span><br/> </span></font></span><span>如若使用一次性水，就不用考虑颗粒问题了。</span></p><p><span lang="EN-US"><font face="Times New Roman"> 罗松</font></span></p><p><span lang="EN-US"><font face="Times New Roman"> 完成于厦门</font></span></p></div> <p>结论是：周期性换水！</p> <p>水对鱼来说是相当的重要</p> <div class="msgheader">QUOTE:</div><div class="msgborder"><b>以下是引用<i>归仙人</i>在2007-7-13 16:15:00的发言：</b><br/><p>结论是：周期性换水！</p></div><p></p> 定期定量换水是养鱼的根本 好东西要回一下
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