Pharmacological Impacts of Antibiotics in Aquaculture Fish

Antibiotics are extensively applied in aquaculture for disease treatment and prevention, yet their use carries significant pharmacological and ecological ramifications. Following oral or bath administration, compounds such as oxytetracycline distribute variably among fish tissues, accumulating preferentially in organs like kidney, liver and gill. Tissue-specific absorption and elimination kinetics determine both therapeutic efficacy and residue persistence, with implications for food safety and regulatory withdrawal periods. Beyond direct toxicity, antibiotic exposure can modulate immune function, alter haematopoietic activity and provoke inflammatory processes, while sub-therapeutic concentrations in water may influence microbial communities and foster resistance. Understanding these multifaceted impacts underpins the development of optimised dosing regimens, mitigation strategies such as immunostimulant co-administration, and policies to safeguard fish welfare, environmental integrity and consumer health.

Research from Nature Portfolio

Recent studies have examined oxytetracycline dihydrate administration in rainbow trout. Following a single oral dose at therapeutic levels, absorption was slow overall but varied markedly among tissues: the gill exhibited the highest uptake rate, whereas plasma absorption was minimal. Peak concentrations differed by organ and elimination half-lives ranged from hours to days, indicating extensive distribution and tissue retention. A 30-day biosafety trial across multiple dosage levels demonstrated sustained feed consumption, stable physiological parameters and low residual muscle concentrations at the recommended dose. These findings support the drug’s safety margin when correctly dosed and inform withdrawal times that balance effective disease control with residue minimisation.

Pharmacological Impacts of Antibiotics in Aquaculture Fish publication trend

The graph below shows the total number of articles in pharmacological impacts of antibiotics in aquaculture fish across all publications each year (not limited to Nature Index journals).

Technical terms

Pharmacokinetics: Study of the processes by which a drug is absorbed, distributed, metabolised and eliminated in an organism.

Bioavailability: Proportion of an administered dose that reaches systemic circulation in an active form.

Cmax: Maximum concentration of a drug observed in a given tissue or plasma following administration.

AUC (Area Under the Curve): Integral of the drug concentration–time curve, representing total exposure to the drug.

Withdrawal time: Interval required for drug residues to decline below regulatory maximum levels in edible tissues.

Haematopoietic tissue: Organ or tissue where blood cell formation occurs; in fish, mainly the head kidney.

References

1. Assessing the effect of therapeutic level of oxytetracycline dihydrate on pharmacokinetics and biosafety in Oncorhynchus mykiss (Walbaum, 1792). Scientific Reports (2024).
2. Effects of Oxytetracycline and Gentamicin Therapeutic Doses on Hematological, Biochemical and Hematopoietic Parameters in Cyprinus carpio Juveniles. Animals (2020).
3. Pharmacokinetics, Tissue Residues, and Withdrawal Times of Oxytetracycline in Rainbow Trout (Oncorhynchus mykiss) after Single- and Multiple-Dose Oral Administration. Animals (2023).
4. Persistent Oxytetracycline Exposure Induces an Inflammatory Process That Improves Regenerative Capacity in Zebrafish Larvae. PLOS ONE (2012).