Approved medicines may be used to treat food-producing animals. There is legislation in place that establishes which teatments are permitted, and Maximum Residue Limits, or MRLs, are placed on various substances and species. The use of non-approved medicines is prohibited. Internationally, MRLs are set by the Codex Alimentarius Commission, but these MRLs are not binding in the EU. Instead, the EU adopts the MRLs outlined in Regulation 37/2010.
In the UK, the Veterinary Medicines Directorate manages the use of veterinary medicines and runs surveillance programmes to monitor for residues in locally produced food and imported food. Port Health officials monitor veterinary residues in imported food according to their veterinary checks regime.
To find the MRLs of pharmacologically active substances permitted in seafood in the EU, please click here; you can also find a list of substances banned in the EU here. Alternatively, you can find more about veterinary residues on the DG Sante website, which also lists major developments to MRLs. The EMA also offers a Q&A page.