Disadvantages of Chemical Treatment
• If used in closed recirculating systems, chemicals may cause adverse effectsor destroy the nitrification processes in biofilters.
• Treatment may have adverse effect on natural food. It may induce oxygendepletion during their degradation, or may destroy algal blooms whosedecay then depletes the dissolved oxygen in the water. It may also inhibitphotosynthetic production of oxygen.
• Chemicals may leave harmful residues in the host.
• Diseased animals do not eat medicated feeds.
• Baths usually do not result in therapeutic tissue level and may be ineffectiveagainst systemic infection.
• Antibiotic-resistant strains may develop.
Some drugs have immunosuppresive effects.