The benefits of using antibiotics in fish (when a bacterial disease has been correctly diagnosed) include:
Treating bacterial infections and reducing illness.
Lowering fish deaths during bacterial disease outbreaks.
Improving recovery, allowing infected fish to return to normal growth.
Reducing economic losses for fish farmers by limiting mortality.
Helping prevent the spread of some bacterial infections within a stock when used as part of a broader disease management plan.
Promote antibiotic-resistant bacteria.
Leave drug residues in food fish if withdrawal periods are not observed.
Be ineffective if the disease is caused by parasites, fungi, viruses, or poor water quality rather than bacteria.