在渔业生产中，由于管理和技术上的原因而引起的鱼病，统称为人为因素。那么，引起鱼病发生的人为因素有哪些呢？一、放养密度不恰当。在养鱼池塘里，每一尾鱼都占有并利用一定的水体．若放养密度过大，则容易造成池鱼缺饵、缺氧，既恶化了生态环境，又加剧了生存竞争，其结果是鱼体生长快慢不匀，瘦弱的鱼就易于患病而死亡。二、混养比例不恰当。不不同种类的鱼，可因食性差异而分别生活于不同的水层，但由于食物链关系，仍会存在争食现象。例如，当鲢、鳙混养时，鲢多、鳙少，一般无多大问韪，如鳙数量超过某一限度，鱼就会因缺饵而营养不良。三、饲养管理不妥善。饲养管理水平的高低，不仅影响鱼产量，而且与fish disease关系密切。投喂不匀，时投时停，时多时少，使池fish hungry or full, leading to diseases such as enteritis. High temperatures without proper removal of grass and algae, infrequent addition of fresh water, and poor water quality can also lead to the proliferation of pathogens and fish diseases.Fourthly, improper technology operation during fishing, transferring fish to different pools or ponds, or transporting fry can cause injuries such as broken fins or scales detached from the body. These wounds create an entry point for microorganisms that can cause secondary infections and lead to outbreaks of contagious fish diseases.

The causes of fish disease due to human factors are multifaceted. Inadequate stocking density in aquaculture facilities leads to overcrowding with insufficient food supply, resulting in malnutrition among weaker fish that are more susceptible to illness. Mismanagement in feeding practices is another factor: irregular feeding schedules may starve some species while overfeeding others; failure to provide a balanced diet contributes further complications. Poor management practices include inadequate maintenance of tanks - including insufficient cleaning and lack of new water circulation - which fosters pathogen growth.

Furthermore improper handling techniques during netting operations for catching aquatic life creates physical damage on the animals' bodies causing lacerations on their skin which may be infected by bacteria leading eventually towards diseased conditions like fin rot.

In summary there are several man-made factors contributing towards occurrence if fishes falls ill these include but not limited too unbalanced stock levels poor nutritional intake substandard tank management under nourishment caused by scarcity coupled with injury induced infection.

Therefore it is crucial that we adopt a multi-faceted approach when it comes addressing these issues so as ensure healthy survival rates amongst our aquatic friends.

Confidence: 95%