Antibiotic Residues in Aquaculture products : the Issue

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As in other animal production sectors, antibiotics are used in aquaculture during both production and processing, mainly to prevent (prophylactic use) and treat (therapeutic use) bacterial diseases.(1) Antibiotics have also been recommended and used as disinfectants in fish handling, but this practice has proved to be ineffective and is generally not approved by the fish inspection services. Antibiotics have not always been used in a responsible manner in aquaculture and, in a number of reported situations, control of the use of antibiotics has not provided a proper assurance of the prevention of risks to humans. FAO, the World Health Organization (WHO), the International Office of Epizootics (OIE) and a number of national governments have already raised the issue of irresponsible use of antibiotics in all production sectors, with particular concern for the potential risks to public health. Many governments around the world have introduced, changed or tightened national regulations on the use of antibiotics, in general and within the aquaculture sector.

Public health concerns

When consumed directly by humans as medicine, antibiotics may cause adverse side-effects, but these can generally be avoided through adhering to the recommended dose and duration of therapy. However, when antibiotics are unintentionally ingested as residues in food, the amount ingested cannot be quantified or monitored and may cause direct health concerns, such as aplastic anaemia, which is said to be associated with chloramphenicol. These direct effects pose significant risks to human health. In addition, the unintentional consumption of antibiotics is leading to the development of antibiotic resistance in bacteria that are pathogenic to humans, and this is another important problem that has not yet received adequate attention. The development of antibiotic resistance by pathogenic bacteria is considered to be one of the most serious risks to human health at the global level.(2) The problem arises when bacteria acquire resistance to one or more of the antibiotics to which they were formerly susceptible, and when that resistance eventually makes the antibiotics ineffective in treating specific microbial diseases in humans.(3) Recognition of the risks associated with the direct and indirect effects on human health of both active and passive consumption of antibiotics has led to bans on the use of certain antibiotics in animal food production (particularly those antibiotics for which no safe residue levels can be determined) and to the establishment of maximum residue limits (MRLs) for those with known risks.

Effects on the industry

During the last year, the detection of chloramphenicol in internationally traded shrimp products has caused much concern. The substance has been found in cultured products, resulting in a slowdown in imports, causing economic loss among the concerned producers and reflecting negatively on all shrimps and on aquaculture overall.

(1) See, for instance: FAO/SEAFDEC/CIDA. 2000. Use of chemicals in aquaculture in Asia, edited by J.R. Arthur, C.R. Lavilla-Pitogo and R.P. Subasinghe. Proceedings of the Meeting on the Use of Chemicals in Aquaculture in Asia, Iloilo, the Philippines, 20-22 May 1996. 235 pp.; and FAO. 1997. Towards safe and effective use of chemicals in coastal aquaculture. Reports and Studies, GESAMP No. 65. Rome. 40 pp.

(2) Updated information on the development of microbial resistance can be found at: See also: K.M. Cahill, J.A. Davies and R. Johnson. 1966. Report on an epidemic due to Shigella dysenteriae, type 1, in the Somali interior. American Journal of Tropical Medicine and Hygiene, 15: 52-56.

(3) P. Shears. 2001. Antibiotic resistance in the tropics. Transactions of the Royal Society of Tropical Medicine and Hygiene, 95: 127-130. F. Angulo and P.M. Griffin. 2000. Changes in antimicrobial resistance in Salmonella enterica serovar typhimurium. Emerging Infectious Diseases, 6(4); and USFDA. 1997. Extralabel animal drug use; fluoroquinolones and glycopeptides; order of prohibition. Federal Register, 62(99): 27 944-27 947.

Taken from « » report,

FAO, 2002

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