Any non-medical and medical use of antibiotics in animals including fishery and shrimp farming will have direct or indirect effect on human health.
The excessive use of antibiotics will lead to increased AMR and these resistant pathogens will disseminate in to environment and humans. Infections associated with these MDR pathogens particularly in immunocompromised patients will causes more morbidity and mortality.
The answer is very simple. If animals and fish are given antibiotics as their treatment measure and if the same animals and fish are consumed then the drugs come into the body of human beings and affect them.