Fish are covered by EU Directive 2010/63 as soon as their larval forms are capable of independent feeding (Article 1). Zebra fish (Danio rerio), however, are the only fish species which have to be bred specifically for use in procedures (Annex I, referring to Article 10).
Under Watering (Section 3.5 of Annex III), the Directive states that provision must be made to adapt the water supply for aquaria and tanks to the needs and tolerance limits of individual fish species.
The species-specific section of this Annex contains only rather general remarks about "fish" (section 11):
11.1. Water supply and quality
Adequate water supply of suitable quality shall be provided at all times. Water flow in re-circulatory systems or filtration within tanks shall be sufficient to ensure that water quality parameters are maintained within acceptable levels. Water supply shall be filtered or treated to remove substances harmful to fish, where necessary. Water- quality parameters shall at all times be within the acceptable range that sustains normal activity and physiology for a given species and stage of development. The water flow shall be appropriate to enable fish to swim correctly and to maintain normal behaviour. Fish shall be given an appropriate time for acclimatisation and adaptation to changes in water-quality conditions.
11.2. Oxygen, nitrogen compounds, pH, and salinity
Oxygen concentration shall be appropriate to the species and to the context in which the fish are held. Where necessary, supplementary aeration of tank water shall be provided. The concentrations of nitrogen compounds shall be kept low.
The pH level shall be adapted to the species and kept as stable as possible. The salinity shall be adapted to the requirements of the fish species and to the life stage of the fish. Changes in salinity shall take place gradually.
11.3. Temperature, lighting, noise
Temperature shall be maintained within the optimal range for the fish species concerned and kept as stable as possible. Changes in temperature shall take place gradually. Fish shall be maintained on an appropriate photoperiod. Noise levels shall be kept to a minimum and, where possible, equipment causing noise or vibration, such as power generators or filtration systems, shall be separate from the fish-holding tanks.
11.4. Stocking density and environmental complexity
The stocking density of fish shall be based on the total needs of the fish in respect of environmental conditions, health and welfare. Fish shall have sufficient water volume for normal swimming, taking account of their size, age, health and feeding method. Fish shall be provided with an appropriate environmental enrichment, such as hiding places or bottom substrate, unless behavioural traits suggest none is required.
11.5. Feeding and handling
Fish shall be fed a diet suitable for the fish at an appropriate feeding rate and frequency. Particular attention shall be given to feeding of larval fish during any transition from live to artificial diets. Handling of fish shall be kept to a minimum.
Annex IV of the Directive describes the techniques for humane killing which may be used on animals covered by the Directive. Here again, "fish" are described collectively. An anaesthestic overdose (where appropriate, with prior sedation), concussion or a percussive blow to the head, and electrical stunning (with specialised equipment) are the only three methods mentioned for fish.
The revised Appendix A of the Council of Europe's convention ETS 123 contains species-specific guidance on accommodation and care of animals used for experimental and other scientific purposes. The Appendix has a section on species-specific provisions for fish, but these are rather general. The text states that species-specific guidance on rainbow trout (Oncorhynchus mykiss), Atlantic salmon (Salmo salar), tilapiine cichlids, zebra fish (Danio rerio), sea bass (Dicentrarchus labrax), Atlantic halibut (Hippoglossus hippoglossus), Atlantic cod (Gadus morhua), turbot (Scophthalmus maximus), African catfish (Clarias gariepenus) is available in a background document elaborated by the Group of Experts who wrote the Convention, but this document is not available. Investigators and animal care staff are requested to acquaint themselves with the characteristics of the proposed experimental fish species, to ensure that appropriate facilities and husbandry procedures are in place before animals are obtained.
The general section of the Appendix also contains a few remarks where fish are mentioned specifically:
Clear instructions on emergency procedures should be prominently displayed. Alarms are recommended for water tanks for fish and other aquatic animals in case of failure of the water or air supply. Care should be taken to ensure that the operation of an alarm system causes as little disturbance as possible to the animals (section 2.6)
In fishes, amphibians and reptiles, tolerance for acidity, chlorine and many other chemicals differs widely from species to species. Therefore provision should be made to adapt the water supply for aquaria and tanks to the needs and tolerance limits of the individual species. (section 4.7.3)
- Code of practice for the housing and care of animals bred, supplied or used for scientific purposes (Fish Section 1 & 2, Chapters 10)
- Animals (Scientific Procedures) Act 1986: A(SP)A'86
- Consolidated version of ASPA
- Guidance on the operation of ASPA
- There is also a section on legislation concerning fish research in the species section of the Norecopa website, and a section on guidelines for fish research.
- Norwegian legislation on animal research also contains text about fish
- Acts and Regulations concerning the Care and Use of Fish in Norwegian Research (Johansen et al., 2005) - some of these documents are no longer in force
- How fish are treated under UK law (Bowles, 5 November 2020)