Fish Diseases and Management

7.3.2.Vaccination vs chemotherapy: advantages and disadvantages

Sl.No	Vaccination		Chemotherapy / antibiotics
1	Prophylactic: few if any losses from a disease	:	Curative: some mortalities before treatment is effective
2	Prophylactic for long duration with only one or two treatments	:	Prophylactic for only a short period; constant treatment required
3	Vaccination: all fish receive treatment	:	Mostly antibiotics are given in food, but sick fish are often anorexic and do not receive treatment
4	No toxic side effects, and healthy fish have better growth performance	:	Toxic side effects may be considerable: treatment relies on differential toxicity between host and the pathogen for a therapeutic index; growth often arrested
5	No accumulation of toxic residues	:	Toxic residues remain: a time lapse is required between treatment and marketing of fish
6	Pathogen unlikely to develop resistance	:	Many bacteria develop resistance to antibiotics
7	No legal restriction on “safe” vaccines	:	Use of antibiotics are restricted due to risk of development of antibiotic resistant strains
8	Theoretically, can control any disease	:	Chemotherapy limited: cannot control viral diseases
9	No environmental impact	:	Chemicals may disrupt local environment