Control of Problem Organisms 



Infectious Diseases and Parasites 



All animal populations are affected to some degree by infectious 

 organisms and parasites. The incidence of infection is increased 

 by high concentrations of fish in intensive production monoculture 

 systems and the stresses resulting from water quality 

 deterioration. High fish populations and high feeding levels bring 

 about a decline in water quality which, in turn, result in animal 

 stress and the incidence of diseases and parasites which would be 

 only minimally or moderately troublesome in natural or 

 semi-intensive production systems. 



The preferred method of controlling disease is to prevent it by 

 simple sanitation and disinfection of equipment and culture 

 facilities and reduction of stress on the animals by maintenance of 

 good water quality, provision of adequate feeds, and use of 

 non-stressful handling, holding, and transportation techniques. 

 Acceptable techniques are generally available but improvements are 

 needed. 



Occasionally, infectious diseases and parasites do become a problem 

 and an appropriate chemical or drug treatment must be applied. 

 Some disease organisms are easily and economically controlled or 

 eliminated, but others are impossible to control with current 

 techniques. 



Aquatic Vegetation , ; , 



Aquatic vegetation includes submerged, emergent, rooted, and 

 free-floating forms, and constitutes many hundreds of species. 

 Some forms of vegetation may be beneficial to aquatic animals for 

 spawning media, protection, or food. However, the same species of 

 plant can adversely affect the growth of aquatic animals through 

 competition. Aquatic vegetation can be controlled by chemical, 

 mechanical, or biological methods. The selection of the 

 appropriate method is based on the characteristics of the 

 production system, the characteristics of the undesirable plant, 

 economic considerations, and environmental constraints. 



In aquaculture, the preferred methods of controlling vegetation is 

 to construct the facility to inhibit plant growth or to maintain 

 plant-eating animals. Chemical control is the only practical 

 method of vegetation control in some production systems. However, 

 relatively few chemicals are registered for aquatic use. 

 Mechanical control is employed only in exceptional cases, due to 

 labor costs and limited benefit. 



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