What is the veterinary prescribing cascade and how does it apply to fish?
In France, the veterinary prescribing cascade allows a vet to use a medicine outside its authorisation exceptionally when no appropriate authorised medicine is available for the species and condition being treated. It sets an order of alternatives and places the decision under the vet’s direct personal responsibility. Fish that produce food follow a different pathway from non-food-producing fish. A prescription is required in both cases.
This answer describes the French framework within EU law. National requirements elsewhere, including in the UK, must be checked separately.
When can a vet use the cascade?
The starting point is a medicine authorised in France for the species and indication, used according to its summary of product characteristics, or SPC. The vet checks its authorisation, availability and suitability for the clinical case. The ANMV medicines index provides authorisations and SPCs; a commercial listing cannot establish that a proposed use is authorised.
The French DGAL guidance on the cascade (in French) explains that suitability rests on scientific and animal-health grounds, rather than price. A shortage at one supplier does not by itself establish that a medicine is unavailable on the market. The guidance does allow a tolerance for some isolated emergencies, which the prescribing vet must assess.
The cascade addresses a documented lack of a suitable treatment. The available products are not interchangeable options. Our Regulation (EU) 2019/6 overview (in French) explains the EU framework.
What is the pathway for ornamental fish?
For fish with non-food-producing status, Article 112 provides the following sequence when no appropriate authorised medicine is available:
- A veterinary medicine authorised in France or another EU Member State, for the same or another species and for the same or another indication.
- If none is available, an authorised human medicine. In France, the DGAL instruction specifies a human medicinal product authorised in France.
- If neither option is available, a medicine prepared extemporaneously in accordance with a veterinary prescription.
The vet moves to a later stage only when the previous stage offers no available option. A human medicine is therefore not automatically the first choice simply because a fish has no dedicated authorised product.
Article 112 also allows a veterinary medicine authorised in a third country as a last resort, for the same species and indication, excluding immunological veterinary medicines. French import requirements still apply.
How does the pathway differ for food-producing fish?
Food-producing aquatic species come under Article 114. Its first level is a veterinary medicine authorised in the EU for a food-producing aquatic species, for the same or another indication.
If that option is unavailable, the article sets out successive recourse to certain veterinary medicines authorised for terrestrial food-producing animals, then human medicines, then an extemporaneous preparation. The terrestrial and human-medicine stages are linked to the list of substances provided for in Article 114(3). Paragraph 2 provides transitional arrangements until that list is established. The vet must check which arrangements apply at the time of prescribing: the sequence alone cannot establish that a particular product may be used.
A veterinary product from a third country may also be used as a last resort for the same species and indication, excluding immunological medicines. All pharmacologically active substances used in these fish must comply with the EU framework governing residues. The cascade cannot authorise a substance prohibited in food-producing animals.
Food-producing status needs to be established before the medicine is chosen. Keeping fish in an aquarium or pond does not, on its own, determine which legal pathway applies.
Who sets the withdrawal period?
The vet sets the applicable withdrawal period for food-producing fish and records it on the prescription. The decision is based on the SPC and, where it does not specify a withdrawal period for the species concerned, the criteria in Article 115.
For fish, some calculations use degree-days, which account for accumulated water temperature over successive days. There is no single fixed withdrawal period for every cascade prescription. The fish farmer must follow the prescription and record the temperatures needed to track that period before setting the harvest date.
Does the cascade permit every antibiotic or imported medicine?
No. Antimicrobials reserved for humans under Regulation 2022/1255 (in French) cannot be used in animals, including under the cascade.
Since 8 August 2026, Regulation 2024/1973 (overview in French) has added prohibitions or conditions for certain antimicrobials used under Articles 112 and 113. These provisions therefore need checking for non-food-producing fish treated under Article 112. This regulation does not govern the Article 114 aquatic cascade and should not be presented as doing so.
Authorisation in another country does not itself permit importation into France. The DGAL instruction requires prior ANMV import authorisation for the medicines concerned. Our FAQ on importing a foreign veterinary anaesthetic distinguishes this process from other experimental uses.
What should the fish keeper do?
A product normally sold without a prescription still requires one when used under the cascade. The vet prescribes the medicine and treatment instructions. In France, the vet may administer it personally or authorise the keeper to do so under their responsibility, in accordance with the prescription.
To help the vet assess the case, provide the species, food-producing status, signs observed, previous treatments and water-quality data. Do not convert a dose intended for another animal or substitute a product found online for the prescribed medicine. Contact the prescriber if the product is unavailable or you have difficulty administering it.
The prescriber chooses the alternative and must check that it meets each condition of the cascade. Vetofish’s therapeutic service can support assessment of the case and implementation of the prescribed treatment.