17. DISEASE CONTROL

Disease control in the hatchery will not be efficient, if any of the three factors- diagnosis, preventive measure or treatment - is omitted. The recommendations to control diseases in the seabass hatchery are listed below:

17.1 DIAGNOSIS

Correct diagnosis, as well as an understanding of the life cycle and ecology of the pathogen, is essential in order to identify a proper control programme.

17.2 PREVENTIVE MEASURES

To control the disease, the following preventive measures should be applied:

1. Maintenance of water quality up to the standard required in a seabass nursery
2. Reduction of environmental stress such as low DO, build-up of waste products, etc., as much as possible
3. Development of resistant disease stocks
4. Vaccine development for immunological protection
5. Environmental manipulation (e.g., growing of larvae in salinities below that at which the pathogen will survive)
6. Regulations to prevent transfer of pathogens from one host population to another
7. Chemical prophylaxis
8. Hatchery sanitation and disinfection.

17.3 TREATMENT

Chemical control should be considered as a "last resort" in disease control. Before treatment, it is better to have baseline information on water quality such as pH and temperature of the culture media. When treating the fish, few fish should be treated to see how they react before treating the entire group. Only those drugs and chemicals which have been cleared by an authorized agency should be used on food fish. Treatments for specific groups of pathogens are suggested in Table 10.